This article looks into convergence processes that involve distinct phonological systems in dialect contact situations, exemplified by the variety of English that developed on Tristan da Cunha, an island in the South Atlantic Ocean. Based on a discussion of the community's social history and an auditory analysis of the segmental phonology of late nineteenth-century Tristan da Cunha English, this article reconstructs the early contact scenario and looks into both phonological convergence and independent innovative mechanisms that accompany new-dialect formation. The data presented here show that dialect contact gives rise to mixing of several inputs (so that ‘new’ dialects draw features from several ancestral varieties), that the interaction of transplanted dialects may also trigger independent, variety-specific mechanisms, and that the interplay of feature retention, input mixing, and local innovation lead to distinctive and (on occasion) endemic varieties of English.