An adjustable book holder includes two primary frames, and one or more auxiliary frames selectively secured between the frames, to increase holding of more books or sheet members to the book holder. The primary frames and the auxiliary frames may be secured together with peg-and-aperture engagements. Two followers may be attached to the frames, and may be coupled between the primary frames and the auxiliary frames, and may be rotatably or adjustably secured to two seats, with gear engagements, to allow the followers and the primary and the auxiliary frames to be secured to the seats at selected angular positions.