A bar clamp having a fixed jaw and a movable jaw which is radially movable over both short and long distances to clamp against a workpiece and is operable using one hand with complete control by the operator at all times. The jaws may either face one another while being mounted on the same side of a handle/grip assembly or face in opposite directions while being mounted on opposite sides of the handle/grip assembly whereby they may be incrementally advanced by the trigger handle/driving lever.