Abstract: A lockset suitable for use on doors of different thicknesses comprises inside and outside knobs mounted on inside and outside spindles which are in turn rotatably supported in inside and outside chassis. Rotation of either knob causes rotation of a rectangular driver spindle to drive a latch operating assembly which retracts a latchbolt. Locking may be accomplished only by pressing a push button located in the inside knob. In one embodiment the push button drives a caliper spring to engage and axially move a plunger bar and in a second embodiment a hook spring carried on the push button engages teeth on the plunger bar. Axial movement of the plunger bar actuates a clutch mechanism to disconnect the outside knob from the driver spindle and lock the outside knob to the outside chassis to prevent rotation of the knob. In the first embodiment unlocking is accomplished by rotating the plunger bar relative to a coupler having a spring thereon for engaging notches on the plunger bar.