Abstract: An interlock mechanism for a multi-drawer file cabinet assembly, for preventing more than one drawer from being opened at a time. The interlock mechanism includes a series of control rods mounted for axial movement within a series of blocks located in the interior of the cabinet. The control rods are arranged in an abutting end-to-end relationship, forming joints therebetween. A pivotable lever is mounted to the blocks adjacent each joint, and an actuator member is mounted to each drawer. Movement of a drawer to its open position causes engagement of the actuator member with one of the levers, to pivot it to a position in which the lever separates adjacent control rods, resulting in upward or downward movement of the control rods and vertical displacement of the joints between adjacent control rods. The remaining levers engage the control rods at a location spaced from a joint between control rods, to prevent the remaining drawers from being opened.