Cambrian rocks of southeastern Newfoundland occur in scattered outcrops, mainly on Avalon and Burin Peninsulas, and comprise a miogeosynclinal sequence of dominantly shaly rocks, with minor limestone, siltstone, and sandstone. The rocks are commonly metamorphosed, poorly exposed and sparsely fossiliferous, and correlation of the various local sequences has hitherto proved difficult owing to lack of faunal control. This report provides detailed stratigraphic sections and systematic descriptions of many genera and species, including seventeen new trilobite species. The faunal sequence is similar to that of western Europe. Three Lower Cambrian zones are recognized with varying degrees of certainty; in ascending order they are named: Coleoloides, Calla via, and Prololenus. Four Middle Cambrian zones are characterized by species of Paradoxides. Upper Cambrian zones of Agnoslus pisiformis, Olenus, and Parabolina occur, and unfossiliferous beds overlying the Parabolina zone may correlate with the Leptoplastus zone of Europe. The youngest Cambrian beds contain Peltura scarabaeoides and are assigned to the Pellura zone. The Cambrian is overlain by Lower Ordovician shales with Shumardia and Diclyonema flabelliforme.