W. H. R. Rivers's "Kinship and Social Organisation" is an anthropological work that examines the function of kinship terminology and its complex relationship with a society's social structure. The book argues that kinship terms do not merely describe biological relationships but also reflect important social arrangements, including rules of marriage, inheritance, authority, and mutual rights and duties. Rivers specifically posits that the origin of "classificatory" terms in kinship systems (which describe multiple kinds of relatives with the same word) lies in the forms of marriage and social organisation (such as cross-cousin marriage and the moiety system) of the societies that use them, emphasizing that purely linguistic approaches have limited scope in determining the meaning of kinship terms and that social custom must take precedence.