This four-volume Major Work contains texts which explore both the foundations of latent variables and factor analysis, and specific contemporary challenges in the field. The collection has been designed as a multi-disciplinary resource, with literature drawn from many different areas of study, such as sociology, psychology, education and political science. In the editor’s introductory essay, a general approach to the meaning and use of latent variables in the social sciences is laid out, the basics of factor analysis and how it works are explained, and the logic that guided the selection of literature included in the collection is elaborated upon. The combination of these elements makes for a truly comprehensive and user-friendly research tool, invaluable to social scientists across a range of disciplines. Volume One: The Conceptualization and Operationalization of Variables Volume Two: Applications of Unmeasured Variables Volume Three: Factor Analysis for Latent Variables Volume Four: Advanced Topics