How and why do languages vary? Studying closely related languages can tell us important details of the nature of human language, by holding most grammatical properties constant while varying others, across a set of languages. Understanding the limits on such variation?and how such differences arise historically?requires an accurate description of a group of related languages. <br/><br/>The heterogeneous varieties of Luyia, a group of Bantu languages of Kenya and Uganda, provide a laboratory for investigating such micro-variation in grammar. This project will produce the first comprehensive descriptions and formal analyses of four underdocumented Kenyan varieties of Luyia: Bukusu, Logoori, Tiriki, and Wanga. A series of monographs will be developed for each language which include a grammatical outline, a detailed description of the tonal system, in-depth studies in syntax, a collection of texts, and a dictionary. <br/><br/>The diverse tone systems of Luyia are a major focus of this work. Luyia tone has many notable features, including a rare process by which High tones spread leftward across and within words. Complex tonal patterns mark inflectional differences among verb tenses, and syntactically conditioned rules are also found in the phrasal tonology. A solid understanding of these processes bears crucially on theories of the phonology-syntax interface, which are concerned with what kind of syntactic information can be used by a phonological system. These theoretically and typologically interesting features of Luyia tone will be systematically investigated through targeted paradigmatic elicitation. <br/><br/>This project models team-based, data-rich and theoretically informed linguistic description and analysis. The Luyia team draws on the expertise of linguists in multiple subfields and brings together US-based and Africa-based scholars, enriching the practice of linguistics by each group. The monographs, text collections, and dictionaries produced by the project will be made freely available online, and relevant materials will be disseminated within the appropriate local communities.