Louis Guttman’s pioneering work on scaling theory is cited in Science (1971) as one of 62 major advances in the social sciences in this century, together with those of Freud, Pavlov, Weber, Keynes and others. Scaling theory led Guttman to develop his non-metric methods for data analysis and facet theory, his crowning contribution. Drawing on a large number of periodicals, books and unpublished papers, this volume offers a representative overview of Guttman’s work and demonstrates its utility for cumulative theory-development in sociology, psychology, education, statistics and other disciplines. The basis of facet-theory, and its applications in fields such as social attitudes and intelligence testing, are presented first-hand. Surprising as it may sound, Guttman’s main interest was in theory rather than method. In fact, he saw the two as inseparable, arguing that 'the form of data analysis is part of the hypothesis'.