Coinage occupies an unusual position in archaeological research. Thriving scholarship on numismatics and monetary history ensures that the objects themselves are well-studied, often seen as an indication of chronology and of stylistic and commercial links. Yet coins might also be analysed as artefacts, and explored as part of the symbolic world of material culture through which archaeologists understand meaning and value in past societies. Using a recently-excavated assemblage of medieval Kilwa-type coins from Songo Mnara on the East African Swahili coast, this article explores the multiple ways that value was ascribed and created through use, rejecting a simple dichotomy between substantive and formal value. Attention is given to the contexts of the coins, which enables a discussion of the relationship between power and the constitution of value, the circulation and use of coins among townspeople, and their use within ritual and commemorative activity.