iPhoto can perform five sorts, or you can move images around manually, which is useful for arranging photos in albums you can use for books, calendars, and slideshows.
To sort photos automatically:
When in any album, choose the desired sort method from the View menu's Sort Photos hierarchical menu (Figure 3.34).
Figure 3.34. To sort photos, choose the desired method from the Sort Photos menu.
From the Sort Photos hierarchical menu, choose either Ascending or Descending to control the direction of the sort (ascending sorts go from oldest to newest, A to Z, 1 to 9, whereas descending sorts go from newest to oldest, Z to A, 9 to 1).
To sort photos manually:
Drag one or more photos to the desired location in the album, as marked by a black line (Figure 3.35).
Figure 3.35. To sort photos manually, drag one or more photos to the desired location, as indicated by a thick black line between photos.
To make iPhoto forget your manual changes, switch to an automatic sort and then choose Reset Manual Sort.
Albums maintain individual sort settings.
iPhoto remembers how you've sorted photos manually even if you switch to another sort order and back to Manually.
You can't sort photos manually in the Library, Last Roll, Last 12 Months, or smart albums, and By Film Roll is available only when you're in the Library album.
iPhoto 6 has replaced the Place Most Recent Photos at the Top checkbox from previous versions with the Ascending and Descending menu items.