This article discusses the evolution of the late Ychsma style. Recent excavations in pyramid complex no III have uncovered a fine corpus of ceramic material which includes complete vessels as well as diagnostic sherds. Radiocarbon dates place the Late Ychsma style from the end of the 14th century to the arrival of the Incas on the central coast. There appear to be two phases in the style, the first of which precedes the Inca regime. The second phase refers to the period under the Incas who introduced new forms and decorative techniques. Manufacturing techniques as well as the evolution of forms and their decoration are given full discussion. Finally a new method of seriation is proposed, which confirms the placement of certain forms and decorative features within these phases.