John Henry Schlegel recovers a largely ignored aspect of American Legal Realism, a movement in legal thought in the 1920's and 1930's that sought to bring the modern notion of empirical science into the study and teaching of law. In this book, he explores individual Realist scholars' efforts to challenge the received notion that the study of law was primarily a matter of learning rules and how to manipulate them. He argues that empirical research was integral to Legal Realism, and he explores why this kind of research did not, finally, become a part of American law school curricula.