It does confirm what I expected Synchronize to do but in my case, it does not seem to work. Here is the repro steps. FileSystem music lib is pointing at the default "Music" folder in Mac OS and is on the primary Mac internal hard drive. Music is organized in folders by artist and then album (there are a few folders where the music is nested up the 3 levels.) I add an mp3 file to an existing folder. Launch beaTunes 4.5 (latest ver) and select the Synchronize command manually. beaTunes shows the Synchronize progress dialog for a couple minutes. I then search for the new song I added to the folder and it is not found. This scenario and behavior is repeatable on my setup.