An adjustable shelf includes a wall mount for coupling to a wall. A fixed post extends downwardly from the wall mount along a first axis. A post assembly has a rotatable tube coupled to the fixed post so that the rotatable tube rotates about the first axis. An arm extends from the rotatable tube along a second axis substantially perpendicular to the first axis. A shaft rotatably couples within the arm and extends from the arm along the second axis, the shaft being rotatable about the second axis between an operational orientation and a storage orientation. A tray extends from the shaft for holding a keyboard. In the storage orientation, the tray is substantially parallel to the wall and, in the operational orientation, the tray is at an angle with respect to the wall. A locking assembly selectively fixes the tray in the operational orientation and the storage orientation.