The drawer itself is large enough to hold unbound A4 papers or A5 notebooks, though it is fairly shallow. My Seven Seas Writer notebook comes to the top edge. The downside to this is that not many pen or pencil cases will fit inside, so writing instruments almost have to go in loose, which isn't going to work well for something that you carry around. The drawer does have a small wooden board that can be inserted to divide the drawer space, if you desire. However, it doesn't have a very tight fit, so mine just ends up rattling around once the box is lifted. Honestly, I've found that piece more useful as a straight-edge for drawing charts in my planner.
Despite the shallow drawer, I find myself using this sketch box a lot. It makes a great lap desk for reading or writing. If I want to sit in my comfy chair while I type, I use this as a surface under my laptop so it doesn't overheat. I do carry some note paper, gel pens, and pencils in the drawer--just not delicate fountain pens. Overall, I really enjoy this sketchbox. Who knows, someday maybe it will be sitting, in disrepair from good use, in an antique shop where it will make someone's day.
(This item was purchased at retail directly from Galen Leather.)