Abstract: An improved two-piece child resistant closure formed from an integrally molded assembly. An integrally molded closure portion connected to a collar portion by a frangible web, is adapted to be forced into an open-topped collar portion. The collar portion defines a recess to receive a closure clutch ring having a greater diameter than the recess defining portions of the collar portion, thereby to retain the closure and collar portions in assembled relationship. The clutch ring defines teeth on its upper surface and the collar portions defines complementary downwardly forcing teeth. The leading edges of the teeth which cooperate in the screw-on mode are generally vertical, and the trailing edges of the teeth which cooperate in the screw-off mode are inclined at a substantial angle to the vertical, whereby unless substantial downward force is exerted in the screw-off mode, the collar teeth are cammed upwardly by the closure teeth to defeat unscrewing of the closure.