I am working on a custom theme in which my gallery page will display a tab for each of three albums. When a tab is clicked the gallery page will show the album contents (title, desc and thumbs) as well as a single large image (depending on the thumb selected) and they do not go to separate album pages. I am looking for the album function that will assign/initialize certain albums to the tabs. All I see is code that loops through the existing albums and displays them all on the page. Each tab needs to be a different "current" album.

You would use the code that goes through the existing albums as a start. Instead of displaying the album thumbnail you would setup each tab. Use the album.php script as a starting point for what to do when the tab is clicked.

OK, that worked. So far so good. Now I need to display the large image in a div within each tab based on selecting a thumb (instead of the thumb linking to a new page).

Please review the functions documentation, specially the methods for the album and image classes. I am sure you will find there what you need.