This page contains complete instructions for migrating from Picasa to Lightroom, or to any other photo manager. The instructions look complicated because they cover many cases. Many of you will be able to skip most of the steps. Read the instructions thoroughly before you dive in and make sure you understand each step, the tradeoffs, and limitations.

Do you really want to use Lightroom?

There are simpler and less expensive photo managers out there. Lightroom will cost you at least $150 per year and it can be cumbersome to use. If you don't need all those features you can probably find a better option that will save time and money. The problem with the other options is that you will lose your Picasa Albums (NOT the photos in them!), your "star" ratings, and the hidden photo attribute.

If you did not use Picasa albums, star ratings, or hidden photos you do not need to use the plugin, and you may not even want to use Lightroom.

Whether or not you decide to use Lightroom, these instructions may still be useful to you. They tell you how to preserve Picasa edits, face data, and other issues related to moving your photos to another organizer.

Please read the instructions carefully, especially if you used Picasa face recognition, if you edited your photos in Picasa (i.e. crop, color adjust, effects), and/or if you have Raw format photos.

Limitations and Special Cases

Many users can simply install and run the P2Lr plugin without doing any preparation. However there are cases where some preparation may be necessary before running the P2Lr plugin

Face Recognition, People, Contacts, etc: If you used Picasa face recognition and want to transfer the faces and names to Lightroom, you will need to run Picasa and save the face recognition data in your photos before importing into Lightroom. The instructions below cover this. If you have already imported your photos into Lightroom, that's OK. That case is also covered.
Picasa edits such as crops and color enhancements: Picasa has a proprietary way of storing image edits which cannot be transferred to other photo management programs like Lightroom. However you can still preserve your edits by following these instructions before running P2Lr.
iPhoto users: If you use iPhoto (or the new Mac Photos) along with Picasa, moving to Lightroom is a little more complicated. iPhoto hides your photos in an internal data structure. Its really just a hidden folder but it is not accessible by Lightroom. To use P2Lr you will need to copy your iPhoto originals to a visible place on your disk, and import your photos from the visible copy. If you want to do this and need help, please contact me.
RAW+JPEG images together: This is only a problem if you have both RAW+JPEG versions of the same photo(s) in the same folder, and have used the JPEGs in Picasa Albums. See this section for details.

System Requirements

Adobe Lightroom Classic, CC Classic, or earlier (will not work with the Cloud version of Lightroom, as it does not support standard lightroom plugins)
Computer running MacOS or Windows as required by Lightroom Classic
Your photos and videos on a local or network disk, with .picasa.ini files in each folder as Picasa left them. This can be a copy from a different location as long as the file/folder structure is in tact
In some cases, it may be necessary to run Picasa to prepare photos for the transfer before importing to Lightroom. See instructions for more info.

Step 1: Back Up Your Photos!

The plugin is very safe. It makes no modifications to your photos or Picasa data, it doesn't even peek at your photos. It only reads your Picasa data files and creates Collections inside Lightroom. All changes it makes to your Lightroom catalog can be undone by deleting the new Collection Set created by the plugin. Even so, you should still run your photo backup procedure (you have one, right?) before you start.

Get all your photos in one place in Picasa

You probably have all your main important photos under one root folder, either the default "Photos" or "Pictures" folder on you OS, or on a separate photo disk drive. However Picasa also grabs photos from anywhere it finds them… your desktop, your User folder, Document folder, etc. Picasa also creates its own "Picasa" folder in your default "Photos" or "Pictures" folder. Sometimes it stashes stuff there by default.

Look at your "folder" view in Picasa and see what photos are scattered around in locations besides your main photo libraty. If you want to preserve those and transfer them to Lightroom, you should move them into folders within your main photo collection that you will be importing into Lightroom. You should move them from Picasa in order to preserve any Picasa data associated with them.

Save your People/Face Data in Picasa

You only need to do this section if you have used Picasa's face recognition feature and want to transfer your People & Face region data to Lightroom. If you have not used the face recognition feature, skip to the next section: "Save Your Picasa Edits".

Note: face recognition is only supported by Lightroom version 6 or newer. If you have an older version and want to preserve face recognition data, you will need to upgrade to Lightroom 6 or newer.

Explanation: By default, Picasa doesn't save Face information in the photos. To transfer your People/Face info to Lightroom you need to tell Picasa to save the Face metadata in your photos.

(Thanks to Rolph Segers from The Netherlands for his help in developing and debugging this procedure and testing on his catalog containing many many faces!)

Run Picasa
Go to the preferences or options screen:
1. Mac: Picasa > Preferences
2. Windows: Tools > Options
Hit the "Name Tags" tab
Check the box "Store name tags in photo"
Hit the "OK" button
Menu: Tools > Experimental > "Write Faces to XMP…"
Hit the "Write Faces" button (see description of other options below)
Coffee break… this could take awhile depending on the number of photos you have. For me it took 17 minutes for 50,000 photos containing 140,000 faces

When its done, all your face recognition data has been saved to your photos so Lightroom will pick it up when you import your photos. However, if you have lots of faces in your photos, you may want to do an extra step to get around a Lightroom limitation and make the import go smoother.

If the number of People is more than 20, or the total number of Faces in your photos is more than 10,000, read the instructions in this section: Pre-Processing Face Metadata, then return here afterwards. Here's how you can get the number of People and Faces from Picasa:

The number of People is on the left sidebar in the People section. Its the number in parenthesis next to the "People" heading.
The number of Face regions can be found by opening the People section and approximating the total of all the numbers shown by each person.

Save Your Picasa Edits

If you did not edit your photos in Picasa (as described at the beginning of this doc), or don't care about saving your edits, you can skip to the next section.

If you made edits in Picasa and want to preserve your edits, read this section before continuing: How to Save Picasa Edits

Import Photos into Lightroom

Note: This section talks about the built-in Lightroom Photo Import function, which has nothing to do with the P2Lr plugin

Before you can use the P2Lr plugin, all your photos from Picasa must be in your Lightroom catalog. You do this by importing using Lightroom's Import function. You may have already done this when you installed Lightroom (and were disappointed to see your Picasa albums and annotations didn't get imported). If you haven't done this before, here are basic instructions for Lightroom Import, or search for instructions from Adobe.

Important Note: If you already imported your photos into Lightroom AND you did the procedure in the section "Save your People/Face Data in Picasa" above, you will need to re-scan the photos in Lightroom to pick up the Face data from them. See the section "Re-Scanning Photo Metadata in Lightroom"

Otherwise, if you have not yet imported your photos into Lightroom, do it now using Lightroom's normal Import procedure.

You must import your photos "in place", leaving them in their current location. Do not copy them to a new location or the Picasa import will not work.

To be safe, I recommend you turn OFF the the "skip suspected duplicates" option.

Install and Run the P2Lr Plugin

Do you really need to use the plugin?

You only need to install and run the Plugin if you used the following features of Picasa and want to transfer that information to Lightroom:

Picasa Albums
Picasa "star" ratings (i.e. "Starred photos")
Hidden photos

If you did not use any of these Picasa features, DONT BOTHER TO USE THE PLUGIN, it wont do anything for you. You can skip this section and go to the section "Fix Person Keyword Associations".

Save the Plugin on your local disk

Downloading the plugin is no longer supported. You should request the plugin from me using the information on the home page. You will receive the plugin in an email.

Open the email and save the plugin zip file somewhere on your local disk where you can find it with your file browser.
Open your file browser, go to the location where you saved the zip file, and unzip it (Mac users: the file may already be unzipped)
Keep the file browser window open because you'll need to find this folder when you install the plugin into Lightroom in the following steps…

Install the P2Lr Plugin

In Lightroom, select menu item: File > Plugin Manager
If you're updating from an older version, remove the old version first by selecting it and hitting the "Remove" button at the bottom
Hit the Add button
Navigate to the folder where you saved the plugin.
Double-click on the "picasa2lightroom.lrplugin" folder.
(Windows note: depending on how you unzipped it, the picasa2lightroom.lrplugin folder may be inside a folder that has a similar name but with a version number after it. e.g. "picasa2lightroom.lrplugin.1-N". Keep drilling down until you are in the "picasa2lightroom.lrplugin" folder.)
Once you have clicked into the "picasa2lightroom.lrplugin" folder, click the "Select Folder" button
You should get a green light meaning the plugin was loaded successfully
Hit the "Done" button

Run the P2Lr Plugin

Now you can run the P2Lr plugin to import all your Picasa albums and star ratings. You only need to run it once. You can run it multiple times if there are errors you need to fix.

Note: If your photos are all under one root folder, skip this note. If your photos are on two or more separate disks, or multiple folders that are not in a common hierarchy, you can import them all in one go. See the support note: Working with Multiple Photo Root Folders

To run the plugin

On the Lightroom menu, select File > Plugin Extras > Picasa Data Import
A folder selection dialog box will open up. Browse to the folder containing all your photos and hit the "Select Folder" button. (If you don't know where your photos are, read this section)

The progress bar in the upper left will show the progress of the Picasa data import:

Looping between 0 and 50% means its searching your photo folders for Picasa data
A quick jump to 75% means it has found all Picasa data and beginning the translation process.
Then it should progress from 0 to 100% as the data is loaded into Lightroom

A popup will tell you when its complete, and if there were any errors.

If there were no errors, You will now have a collection set called "Picasa Import" suffixed with the date and time of the import. Look on the left side of the screen under "Collections". You may have to expand the "Collections" section using the little arrow. You should see a Collection Set with a name like "Picasa Import 2017-01-27 09:30:00". Open it using the arrow to the left of the name. Inside that Collection Set you should find multiple collections:

A Collection for each of your Picasa albums
A Collection containing every photo that has a Picasa star rating

Note: If you did not have any albums in Picasa and did not assign "stars" to any of your images in Picasa, the collection set will be empty.

If there are errors, or no errors but nothing was imported, go to this section: Dealing With Errors

Fix Person Keyword Associations

You can skip this section if you:

Don't have any People/Face data from Picasa in your photos. or…
You have many People/Faces in your photos AND you ran the extra "ExifTool pre-processing" step to pre-process your photos. Doing the ExifTool pre-procesing avoids having to do this procedure.

If either of the above are true, skip to the next section: "Other Post-Processing"

Explanation: As of this writing, there is a problem with transferring the XMP person data from Picasa to Lightroom. Lightroom doesn't associate the XMP people/name metadata to the photo from which it came. That is why you see the Person Keywords in the Keyword list in the Metadata view, but they have zero photos associated with them (i.e. the number 0 next to each name. If you see non-zero numbers then Adobe may have fixed this). Here's how to change those zeroes to non-zero references to the photos:

In the right sidebar, expand the "Keyword List" section (using the little arrow)
You should see the names of all the people in your photos (You can filter "people" tags by expanding the filter text box and selecting "People" filter)
Are there zeroes next to each name? If so, its because of the problem described above. If the numbers seem to be the correct number of photos in your collection that include each person, then the problem has been fixed in Lightroom, so you can skip the rest of these steps. If you see zeroes, the workaround is pretty quick and easy:
Expand the "Catalog" section on the left sidebar and select "All Photographs"
Switch to "People" view, using the button below the view window with a face on it. If you have many photos and people, this will take awhile, and Lightroom may freeze for several minutes while it processes the people in your photos.
You should now see all People in your photos with the correct name labels in the main center window under "Named People"
Click on the first face image to select it
Hit Shift-o (i.e. "Edit Name" in the context menu)
Without editing the name, hit the Enter key. This "fake edit" should cause the entry for that person in the Keyword List to be updated with the number of photos with that person. If there are many photos associated with this person, it can take awhile for Lightroom to process. (this is why I suggest "Pre-Processing Face Metadata" if you have lots of People and Face regions)
Repeat steps 7-8 for each person under "Named People"

Dealing With Errors

If there were no errors, but it says nothing was imported, it could be because you didn't have any Picasa Albums or Starred images. Run Picasa and see how many Albums (NOT Folders) and Starred Images you have. (if you don't know how, its described in the section "How to Verify all your Picasa Data was Imported")

If the popup at the end says there were errors, follow these steps:

Locate the log file p2Lr.log. You will find it in your Documents folder, or in a sub-folder depending on your Lightroom version (for example, the latest Lightroom Classic puts it in Documents/LrClassicLogs)
Open the log file with a text editor.
Note: If you have run P2lr multiple times, there will be entries in the log file for every run, so search for the last occurrence of the text "Starting p2Lr"
Find the lines containing "ERROR" for clues to the cause of the errors. The most common causes will be:
1. The photos were not imported into Lightroom before running the P2Lr plugin. Double check to make sure the photos in the error message are visible in Lightroom. If not, you'll need to import the folder that contains all your photos. See the section "Import Photos into Lightroom"
2. There were JPEG and Raw files together in the same directory. See the "Limitations and Special Cases" section for more information.

After resolving the problems, simply run the P2Lr Picasa Data Import function again. It will create a new Collection Set with a new date/time stamp. You can delete the old Collection Set from the previous run any time.

Additional Topics

This section contains supplemental information referenced in the main instructions above.

How to Verify all your Picasa Data was Imported

Follow the steps below to verify all your Albums, Stars, Faces, Captions, and Tags from Picasa were successfully imported into Lightroom.

Albums

In Picasa on the left side of the screen, the Albums section should have a number next to it in parenthesis.
Take that number and subtract 3 (for the 3 "automatic" albums: Emailed, Updated, Starred).
The number should match the number of Lightroom "Album" collections imported by P2Lr

Starred Photos

In Picasa on the left side of the screen, open the Albums section
If you have any starred photos, there should be an Album called "Starred Photos" with a number next to it.
That number should match number of photos in the "Picasa Starred Photos" collection in Lightroom.

People and Faces

In Picasa on the left side of the screen, the "People" section should have a number next to it in parenthesis, that is the number of people in your photos. If you open the People section, the numbers next to each person is the number of photos containing that person.
In Lightroom, to find the number of people, go to the Keyword List on the right sidebar and expand it using the small arrow next to "Keyword List". Under the "Filter people" box, select "People" to display just the People Keywords. The number of people in the Keyword list, and the numbers next to each name should match the numbers in Picasa.
In Lightroom, select a Person keyword and click on the little white arrow to the right of the name and count.
All the photos with that person should appear in the middle window
Double-click one of the photos to open it. Pick one with multiple people in it.
In the toolbar below the image, click the icon that looks like a picture frame with "N named people" next to it. (N=some number)
Boxes should appear around each face with name labels

Warning: do not switch to People view (the icon with the face at the bottom of the view window) while in a context containing more than a few thousand photos (context is what's selected on the left sidebar). There is a problem with Lightroom; if you have more than a few thousand photos in People view, it will freeze while it processes all the face data. It will eventually return, but it can take more than an hour depending on the number of photos and your computer's processing ability.

Captions

Captions are not as obvious in Lightroom as they were in Picasa. You have to configure Lightoom to display captions if you want to see them all the time. Heres how to verify your captions are there:

Identify a photo in Picasa that you know has a caption
Locate the photo in Lightroom
On the right side of the screen, open the "Metadata" section using the arrow next to the heading
You should see the caption in that metadata window, below "Title"

Tags

Tags become keywords in Lightroom.

In Lightroom, open the "Keyword" section on the right side of the screen
you should see a list of all the tags you put on photos in Picasa (along with all the names of the People in your photos)
Find a keyword that is not a person's name
The number indicates how many photos have this keyword
Click the arrow next to the number
You should see all the photos to which you assigned that Tag in Picasa

Pre-Processing Face Metadata

As of this writing, there is a problem with transferring the XMP person data from Picasa to Lightroom. Picasa only saves one of the two face tags expected by Lightroom. As a result, when you import your photos, Lightroom will have a list of People keywords, but no photos are associated with them. The workaround in Lightroom (described in the section "Save your People/Face Data in Picasa") is simple, but can be long and tedious if you have many People, or many photos containing named People. Following the additional steps below allows you to skip that time consuming workaround.

If you decide to do this, I recommend you do it before importing the photos into Lightroom. If you have already imported your photos and don't want to start over with a clean catalog, then you will need to re-scan the photos in Lightroom after you do the steps below. Re-scanning is described in the section "Save your People/Face Data in Picasa". Re-scanning will take longer than a clean import, and may have some undesirable side-effects if you've edited the photos' metadata in Lightroom.

Here is the procedure for pre-processing all your photos to add the name tag that Lightroom expects:

Download and install ExifTool, which is available for Mac and Windows:
- Mac OS:
  - Download the "Mac OS X Package" from the home page: ExifTool
  - Install it using the instructions on the "Installing ExifTool" page
- Windows:
  - Download the "Windows Executable" from the ExifTool Home Page
  - unzip the executable somewhere (preferably a folder in your path)
  - Rename the executable from "exiftool(-k).exe" to "exiftool.exe"
  - Add the folder to your path, or remember the full path to the executable "exiftool.exe"
  - For more details, see the windows installation instructions
Open a console window (i.e. "Terminal" on Mac, or "Command Prompt (cmd)" on Windows)
Use the "cd" command to switch to the base folder that contains all your photos. (If you don't know where your photos are, see How to locate your Picasa photos)
Copy and paste the following command into the window, including the quotes and the dot at the end:
- Windows: exiftool -q -q "-xmp:subject+<regionname" -r .
  (Note: On Windows, if you didn't put ExifTool in your path you will need to specify the complete path to the executable, e.g. c:\path\to\exiftool\exiftool.exe)
- Mac OS: exiftool -q -q '-xmp:subject+<regionname' -r .
- Note: the double "-q" tells ExifTool to supress warnings. There will likely be many warnings about minor issues with your photos' metadata. If you want to capture and review all the warnings, remove the two "-q" arguments and redirect the output to a file by appending this to the end (with spaces, without quotes):
  " > exiftool.log 2>&1"
Coffee break… For me this took 20 min for 50,000 photos containing 140,000 faces
After it finishes, if you want to view the metadata that was written, you can run this command:
exiftool -xmp:subject -r . > meta-xmp-subject.txt
Then open the "meta-xmp-subject.txt" file in a text editor. You should see a list of the people names in each image file.

That's it! Now you can return to the main instructions where you were before being diverted to this section. But first… note that ExifTool saved the original image file for every file it modified. These have "_original" appended to the file name. You might want to hang on to these until you verify that everything worked. They wont get in the way, they just take up space. Later you can use Finder or File Explorer to search for *_original, and move or delete them.

Re-Scanning Photo Metadata in Lightroom

If you imported your photos into Lightroom, and then afterwards you saved the People/Faces metadata as described in the section "Save your People/Face Data in Picasa", you will need to re-scan the photos in Lightroom to pick up the new face metadata that Picasa wrote to them. Follow these steps:

Run Lightroom
Expand the "Catalog" section on the left sidebar (using the little arrow)
Select "All Photographs"
Make sure you are in thumbnail grid view (use the grid button below the main view window on the left)
Menu: Edit > Select All (or Ctl-A)
Menu: Metadata > Read Metadata from Files
Read the warning. If you've previously used Lr to edit other metadata on your photos it could overwrite your edits (if you don't know what I'm talking about you're probably OK)
Hit the "Read" button
Coffee break… it will take awhile if you have a lot of photos. About 1-2 minutes per 1000 photos. Watch the progress bar in the upper left corner.

When it completes, you should see People Keywords in the Keyword List with the names of all the people in your photos. The Keyword List is on the right sidebar in Lightroom. This is explained more in the section How to Verify all your Picasa Data was Imported.

How to Import your photos into Lightroom

These instructions are provided as a quick overview of the standard procedure for importing photos into Lightroom. For more details, see the Lightroom documentation and help pages.

In Lightroom, hit the Import button in the lower left.
Navigate to the folder where your photos are stored. (If you don't know where they're stored, see these instructions: How to Locate Your Picasa Photos)
On the upper left under "Source" make sure the "Include Sub-folders" is checked
At the top, make sure "Add" is selected. You want to Add the photos to the catalog in their current location on your disk without moving them.
On the right side of the screen, make sure you UN-check the option "Don't Import Suspected Duplicates". You DO want to import suspected duplicates. Otherwise it will only import the Picasa-edited photos and it will skip over your original photos. If there's a check mark by this option click on it to turn off the check mark.
Hit the Import button.

If you have a lot of photos this will take awhile… maybe an hour…

How to Locate Your Picasa Photos

These instructions will help you find where on your disk your important photos are stored. By Important I mean photographs that you want to view and organize in Lightroom. You need to know where they are on your disk so you can import them and their Picasa data into Lightroom.

Menu: View > Folder View > Tree View
On the left side of screen, open the "Folders" section by clicking the red arrow
Figure out where your important photos are stored. Under the top level "Computer" folder (named "My Computer" or similar), there will be one or more sub-folders. Your photos will likely be in a folder called "Pictures" or "Photos" unless you've intentionally put them somewhere else (such as a different disk or data directory). If all of your important photos are in the standard "Pictures" folder, then you can skip the next step
If your important photos are in one or more sub-folders other than "Pictures", you need to note where those folders are on your disk, as follows:
1. Right-click on the sub-folder and select "Locate on Disk"
2. This will open a File Explorer or Finder window showing where your photos are
3. Note the location on disk (write it down or save in a text file). You will need to know this when you import into Lightroom. For example:
  Mac: /home/Joe/photos
  Windows: C:\Users\Joe\photos
4. Repeat for each sub-folder under "Computer" where important Picasa photos are stored

How to Save your Picasa Image Edits

When you edit a photo in Picasa, it doesn't actually change your original image file. This is good because it preserves your original photo exactly as it came from your camera. Picasa stores edits as instructions which are interpreted by Picasa when you view the photo. Unfortunately these edit instructions are proprietary so they cannot be transferred to other photo management apps like Lightroom.

So the only way to retain crops and image enhancements is to run Picasa and save them to disk before you import them into Lightroom. When you do this, Picasa saves your original images in a sub-folder so you still have the untouched image from your camera.

If you don't want to save the crops and image enhancements made in Picasa, you can skip this step. If you skip this step, you will still preserve albums, stars, captions, tags, and faces. You'll only lose the crops and color tweaks you did.

Steps to save Picasa image edits

If you only have edits in a few folders, use the first procedure. If you have many folders with edited images, use the "Simon Deichsel" tip below to save all.

Launch Picasa
Collapse your album view to get it out of the way
Menu: View > Folder View > Flat Folder View
Now the Folder View shows only folders that contain photos that picasa knows about.
Starting at the top, click on the first folder.
In the photo grid window, below the folder name, find the "Save edited photos to disk" button:
The button may be grayed out, which means you have no edits in that folder, so go on to the next folder.
Press the "Save edited photos" button if its not grayed out
Hit the Save button on the popup confirmation
Repeat for each folder on the list

Alternative to save all your edits in one operation (Thanks to Simon Deichsel for this tip!)

Launch Picasa
In the search box at the top right of the screen, type "*.jpg"
IMPORTANT: hit "Enter" in the search box after you type "*.jpg"
A green "filter" bar appears below the search box that says "Displaying N Pictures in M Albums".
Below the green bar, click the "Save edited photos to disk" button:
(On Mac OS, if the save button is grayed out, jiggle the zoom slider and it should appear)
Repeat the above steps for the file type "*.jpeg" and any other file types you might have edited. Most likely you only edited jpg/jpeg's.

Your originals are now stored in in sub-folders named ".picasaoriginals". Unfortunately Picasa makes these folders "hidden". Lightroom's import process wont see these hidden folders, so if you want to import the originals (in addition to the edited version) you have to un-hide the folders, or import them manually in Lightroom. If you don't un-hide these folders, everything will work OK, you just wont be able to see the originals in the sub-folder when using Lightroom.

Here's how to Un-hide the sub-folders with your original photos in Windows. (In Mac you may need to rename the folders so they don't begin with a dot.)

Procedure for Windows users:

In Windows file explorer, navigate to the base folder where all your photos are.
In the search box in the upper right, copy and paste this, including quotes: name:".picasaoriginals"
You will see a list of folders by that name
Select them all
Right-click on the highlighted group and select "Properties"
Uncheck the "Hidden" attribute
Hit OK

Now these folders will be visible to Lightroom and can be imported. If you have already imported your photos, you can repeat the Lightroom import to add the newly visible photos.

Details of Picasa Data Types

Here is an explanation of the various features Picasa supports, and how they can be transferred to Lightroom:

Albums: the term Picasa uses for collections of photos you create using photos from one or more folders on your disk. Albums are defined in Picasa data files. P2Lr collects Album data from the Picasa files and reconstructs the albums as Collections in Lightroom
Image Edits (crops, color enhancements, and effects): Picasa has a proprietary way of storing image edits which cannot be transferred to other photo management programs like Lightroom. If you want to preserve your crops and photo edits, follow these instructions before running P2Lr.
Faces/People: Picasa's face recognition and people info is stored in the Picasa data file. P2Lr reads this info and collects all images for each recognized person in a separate Lightroom Collection with the persons name.
Star ratings: Picasa star ratings are stored in the Picasa data files. P2Lr reads the data and creates a Lightroom Collection containing all the photos that are starred in Picasa. Once you have them in Lightroom, you can select them all and assign a Lightroom star rating of your choice, between 1 and 5.
Captions: The text captions you entered in Picasa are stored inside your photo file, so when you import your photos into Lightroom, the captions will be preserved.
Tags: The tags you created and used in Picasa are stored inside your photo files, so when you import your photos into Lightroom, the tags will be preserved and usable in Lightroom.
Uploaded Albums: Lightroom includes photo sharing on Adobe's website, just like the old picasaweb online albums. Once your Albums are imported as Lightroom Collections, you can upload them to the Adobe website.

Why Smart Collections Don't Make Good Albums

Be leery of any photo import process that organizes your photos in Lightroom "Smart Collections". This type of collection is not a good way to represent your Picasa albums. P2Lr imports your Picasa Albums as Collections in Lightroom. It creates permanent Collections, not dynamic "Smart Collections" as some other procedures do.

Smart Collections are dynamic, and may have random extra photos in them or they can become corrupted in the future by new photos. A Smart Collection collection using filenames will pull in any and all photos with a matching name. For example, say you have a photo with a file name of "IMG001.jpg" in your Album called "Disneyland". You used some other (non P2Lr) program or process to import it to Lightroom and it put it in a "Smart Collection". Now, if you have any other files anywhere in your photo collection with the same name "IMG001.jpg" they will show up in your Disneyland collection too. And… if you get a new camera in the future and your first photo with it is named "IMG001.jpg", guess what? Its going to automatically get added to your Disneyland collection too. Smart Collections are not intended to be used for static albums which is why P2Lr does not use them.

If you have already used a different procedure or program that created Smart Albums, you should still run P2Lr to create regular Collections. Later you can delete the Smart Collections.

Raw + JPEG Sidecar Problem

Some cameras can optionally produce both RAW and JPEG images in the same shot. If you have RAW and JPEG versions of the same pictures in your folders, then Lightroom will only "see" the RAW image. If your Picasa albums use the JPEG image, then Lightroom will not be able to find the JPEG image so it will not show up in the album

Why? When Lightroom sees two files with the same name in a disk folder, it assumes one is a thumbnail or "sidecar" and ignores it. This can happen when you have a JPEG and Raw version of an image, or video and an accompanying thumbnail. Since they have the same name and are in the same folder, Lightroom will not import the JPEG image because it considers the JPEG a thumbnail or "sidecar" and ignores it. If you use the JPEG image in your Picasa albums, then when you run P2Lr, it will not be able to find the JPEG file and therefore it will produce an error.

One way around this is to move your Raw files to a different location, or put them in a sub-folder so they are not together in the same folder.

If this is a problem for you, let me now. If I get enough requests, I'll add a workaround in the plugin.

Picasa XMP Write Options

This describes the 3 options under Picasas "Write faces to XMP" operation.

Write Selected – Writes the face tags only into the photos that are selected before running the function.
Write Faces – Writes all face tags into photos that have face tags. This doesn't touch photos that don't have face tags.
Write All – Writes XMP tags into all Photos whether they have faces or not. Makes sure all photos have XMP tags whether or not there are any faces in the Photo.