What is the role of language in how we manage our relationships with other people? This dissertation project investigates this question from the perspective of a Tanzanian language called Datooga, which has a special respect vocabulary used only by women. Out of respect for their husbands' families, married women avoid saying the names of their in-laws, as well as any ordinary words in the language that sound like these names. To be able to talk freely while still observing the taboo, Datooga women have developed an entire additional vocabulary, distinct from that of the ordinary language. "Avoidance registers," as these special vocabularies are known, are rare across the world's languages, but have arisen independently in several parts of Africa, as well as in Mongolia and Australia. Unfortunately, we currently have an incomplete picture of how these avoidance registers work, because most previous research has relied on interviews with speakers rather than observation of actual speech. This dissertation project will provide the first comprehensive documentation of an avoidance register in everyday use.<br/> <br/>Avoidance registers are important for the study of language because they illustrate strikingly the social function of language; they are motivated solely by interpersonal concerns relating to gender, kinship, and social status. To explore the social dynamics of the Datooga avoidance register, this project involves collecting, transcribing, and analysing audio-visual recordings of spontaneous interaction in Datooga homesteads, as well as compiling a database of avoidance vocabulary. Fieldwork will be conducted in Manyara Region, Tanzania, and data will be collected from several families across the region. This project will significantly advance our understanding of linguistic avoidance and its role in social life, while also building on our knowledge of an understudied language and making a unique contribution to the documentation of the world's linguistic diversity.