Abstract: A lockable spreader clamp comprises first and second handle portions for gripping by an operator and first and second arm portions extending therefrom. Outer portions of the arm portions have contact pads thereon for engaging a work piece. Inner portions of the arm portions are hinged together and cooperate with the handle portions so as to be responsive to movement thereof, so that movement of the handle portions towards each other causes the outer arm portions to move away from each other. The arm portions are locked to engage the work piece when the handle portions are moved towards each other to activate a locking structure, and can be released from a locked position by activating a releasing structure. The invention can be positioned in a narrow space between two members of a work piece using one hand, and can be locked in position so as to be self-supporting and leave the operator's hands free. When so locked, the clamp can provide an anvil for hammering against.