Caijia, [me?²¹ni³³?o?³³] ‘Caijia speech’, is an endangered language in the Sino-Tibetan family with less than 1000 speakers in Hezhang and Weining counties in northwest in Guizhou Province in Southwest China. Its sub-classification remains unclear. It was almost four decades ago when the Caijia language was officially reported for the first time in 1982 by the Language Team of Bureau of Ethnic Identification in Bijie, yet this language has nevertheless remained neither well-described nor studied. This book, a linguistic description of the Xingfa variety of Caijia based on the fieldwork data in Xingfa township of Hezhang county, is the first reference grammar of the Caijia language, covering its sound system, word formation, parts of speech and syntactic structures in fifteen chapters. Being analytic, Caijia presents many common grammatical features attested in East and Southeast Asian languages, for example, compounds, quadrisyllabic idiomatic expressions or elaborate expressions, lack of inflection, a classifier system, a strong relationship between nominalization and relativization, pro-drop and grammaticalization of verbs. Moreover, Caijia shares more similarities with Sinitic languages. Apart from these common areal features, this book will also reveal some special features of Caijia.