Scientific realism has been advanced as an interpretation of the natural sciences but never the behavioral sciences. This exciting book introduces a novel version of scientific realism—Measured Realism—that characterizes the kind of theoretical progress in the social and psychological sciences that is uneven but indisputable. Trout proposes a theory of measurement—Population-Guided Estimation—that connects natural, psychological, and social scientific inquiry. Presenting quantitative methods in the behavioral sciences as at once successful and regulated by the world, will engage philosophers of science, historians of science, sociologists of science, and scientists interested in the foundations of their own disciplines.