Abstract: A folding knife with positive lock for maintaining the knife blade selectively within the handle case and in open position. A spring urged foot engages appropriate locking notches on the blade for open and closed positions to render the blade immobile in either position. A thumb actuated rocker (several embodiments are disclosed) releases the foot from contact with the notch and out of the path of blade rotation. In an alternate form a pull ring may be used as the lock release. A positive stop on the knife blade abuts the handle case when the blade is in closed position to facilitate movement to its open position when the foot has been removed from the closed locking notch.