AbstractThis chapter offers an overview of historical and archaeological research on Islam and Islamic practice on the pre-colonial eastern African coast during the late first and early second millennium ce. Due to the visible remains of mosques, tombs, and other stylistic elements influenced by the Islamic heartlands, researchers have always regarded Islam as important to the emergence of Swahili coastal towns. In this way, the archaeology of the Swahili has always been an archaeology of Islam. Archaeological research during the past thirty years, however, has challenged the way an earlier generation of archaeologists characterized Swahili society as resulting from immigrant settlers from the Arab world. These debates, which continue today, are centered on how researchers position the Swahili within the dar al-Islam: Are they increasingly marginalized descendants of early colonists or the result of cosmopolitan engagements of local communities? Uncovering the first-millennium roots of east African Islam has allowed archaeologists to explore the development of coastal Islam, its particular material legacy, and its possible sectarian associations. Building on this research, the authors argue for a shift in research emphasis, from the study of Islamic presence to that of Islamic practice and demonstrate how research on mosques, burials, and coins can provide insights into the way coastal residents enacted Islam in their daily lives.