Abstract: Self-adjusting pliers include first and second elongated members each having at one end a jaw portion and at the other end a handle portion, with the elongated members pivotally connected at a position intermediate the jaw and handle portions such that upon positioning the jaw portions on a workpiece and squeezing the handle portions toward each other, the jaws adjust to thickness of the workpiece as they grip the workpiece. The pliers further include a ratchet locking mechanism between the handle portions, the locking mechanism adapted to releasably secure the handle portions upon squeezing of the handle portions toward each other and gripping of the workpiece by the jaw portions to prevent the handle portions from moving apart. A cam operated adjustor is connected to the locking mechanism to increase pressure of the jaw portions about the workpiece, after securing, by hand pressure alone.