In the social sciences, phenomena tend to be hierarchically structured, so that individuals belong to groups, and groups belong to larger organizations and societies. Multilevel research stresses this hierarchical structure of social life, and necessarily assumes the existence of a particular organization of the procedures of investigation. This organization, which is fundamental to the research, is called a "research design." Because the research is hierarchical, it uses a "multilevel design." This book provides a detailed overview of the theoretical and methodological aspects of multilevel research based on the multilevel definition of social structure. Six chapters discuss the foundations of multilevel research and the applications of its research in the social sciences. An annotated bibliography follows, which is divided into eight sections on theoretical and methodological issues and on applications of multilevel research. Included are books and articles published from 1980 through 1993.