Abstract: A tamper evident cap designed for threading onto a container by conventional bottle capping machinery. The cap includes a first set of spaced-apart lugs for engaging a second set of spaced-apart lugs of a container. The lugs of the cap and the lugs of the container neck are constructed to slide relative to each other upon threading of the cap onto the container while engaging each other to prevent unthreading of the cap from the container. The container neck is especially suited for glass bottles which must be blow molded. The cap includes a first skirt portion and a separable strip, and may include a second skirt portion that remains on the container neck after the separable strip has been removed. The gap between the skirt portions left by removing the separable strip indicates that the cap has been tampered with.