All readers can hold hundreds to even over a thousand books. It depends on how much memory your reader has and the size of the books. Some readers have expandable memory. My Sony has slots for two memory cards (each one has a limit of 8 gigs) so I can have a total of 17 gigs of memory which includes the 1 gig that is on the reader. The downside to the memory cards is it takes more time for the books to load. My reader remembers the page I stopped at on multiple books. I can be reading 4 or 5 books and be in a different place in all of them and when I open the individual book the reader knows where I stopped.