Abstract: A book carrier organizer tray includes a base sized for resting on a book carrier shelf. The base includes a top surface and a plurality of sides. The top surface of the base includes a writing surface, preferably inclined, and defines a plurality of receptacles. The writing surface includes a front edge, a rear edge and a pair of side edges. The elevation of the front edge of the writing surface is lower than the elevation of the rear edge. The receptacles are adapted for receiving articles of different sizes and shapes. The tray is combinable with a mobile book carrier which comprises a frame and a plurality of rotatable members. The frame includes a plurality of supporting members which define a plurality of book receiving surfaces or shelves. The organizer tray is carried by one of the book receiving surfaces.