 <p>There is a 2GB limit for <em>apps</em> from the App Store but as far as user data goes, you should be able to basically fill the disk. When that happens, your saves will start to fail, I believe with 'NSFileWriteOutOfSpaceError' bubbled up from the PSC.</p> <p>As far as limiting entity space, there's no Core Data support for this - you'd have to handle it programatically. You could extend the validation system to check for certain conditions (free space, number of entities) and fail an insert or update if these didn't match your criteria.</p> <p>If you want to delete old users, just sort the results and delete the first/last one.</p>