A variable reach device for attachment to a boom of a lift truck to increase the range of movement of a fork carriage of the lift truck. In one embodiment, the device has a mast connected at one end to the boom and an arm pivotally connected at one end to the other end of the mast. The fork carriage is pivotally connected to the other end of the arm and its attitude or orientation is controlled during movement of the arm. In another embodiment, the reach device provides a purely horizontal movement of the fork carriage to extend the fork carriage away from the boom as the device unfolds and to retract the fork carriage back towards the boom as the device is folded. In this embodiment, the fork carriage is slidably carried by the arm via a lift chain connected to a cam which rotates in proportion to the rotational movement of the arm relative to the mast. The cam is designed to let out or take up the lift chain in proportion to the vertical component of the movement of the free end of the arm as it pivots about the mast to maintain the constant vertical height of the fork carriage as it is laterally advanced and retracted.