Rhyolite is found in several late Cenozoic volcanic areas in Papua New Guinea including (1) New Britain and islands to the north, where rhyolite compositions correspond to different depths to a Benioff zone, (2) the St. Andrew Strait area in the northern Bismarck Sea, where alkali rhyolites are the only rock types found on Tuluman, Lou, and Pam (TPL) islands, (3) the Moresby Strait area in the D'Entrecasteaux Islands, where alkali rhyolites similar in composition to the TPL rhyolites are found together with basalts, andesites, and dacites, and (4) the Dawson Strait area, also in the D'Entrecasteaux Islands, where the rhyolites are comenditic (peralkaline) and markedly different from all other rhyolite types known from Papua New Guinea. The TLP and Moresby Strait rhyolites are thought to have been formed by partial melting of mafic crust, whereas the peralkaline Dawson Strait suite has apparently originated by crystal fractionation. Crystal fractionation has also been proposed as the cause of rhyolite genesis on Willaumez Peninsula and at Rabaul in New Britain. However, the supporting evidence is not conclusive, and partial melting of young arc crust is a more acceptable alternative, at least for the abundant rhyolites of central Willaumez Peninsula.