A fruitful methodology for tracing the development of grammatical complexity has been the examination of centuries of written texts. Yet written documents necessarily remain silent about the prosody of the evolving constructions. An awareness of prosodic patterns can further our understanding of the emergence of complex constructions in several ways. The focus here is on early stages of development of individual constructions within a language, first when prosody is the only indication of complex structure, then when emerging marked constructions are still very young. Processes of development are illustrated with developing complement and relative constructions in Mohawk.