Shelves are adjustable, but I've never seen extra shelves available on the side. However, each one comes with four adjustable shelves in addition to permanent ones in the middle and bottom, and if you use all four it would hold six rows of CD jewel cases with little wiggle room. Using two of the shelves would hold four levels of VHS/DVD cases with room to spare. If you're familiar with the old Sega Saturn/Sega CD plastic cases, they're the perfect height for those. There's really no reason to add more shelves unless you're storing something significantly shorter than a typical CD jewel case.