A quick acting cam lock vise for use with drill presses and the like comprises fixed and movable jaws mounted on an elongate mounting bar. A spring urged over center toggle linkage is connected with a movable jaw and is operable to cam the jaw into gripping relation with the work piece, and is also operable to releasably lock the movable jaw with respect to the mounting bar. The toggle linkage includes a lock actuating member operatively connected with a pair of concavo-convex locking elements which grip the mounting bar when the toggle linkage is in the locking position.