We describe the development of FAD-Plus, a 27-item measure of lay beliefs in free will and 3 closely related constructs: scientific determinism, fatalistic determinism, and unpredictability. Previously published measures included only a subset of these variables and tended to assume an a priori pattern of relations among these 4 beliefs. In Study 1, exploratory factor analyses suggested relatively independent factors. This independence was sustained in Study 2, using a confirmatory analysis. Each of the 4 subscales (Free Will, Scientific Determinism, Fatalistic Determinism, and Unpredictability) showed acceptable internal consistencies. Study 2 also mapped out associations with the Big Five personality traits and showed that believing in free will is not synonymous with having an internal locus of control. Study 3 replicated the instrument's structure and subscale reliabilities in a community sample. Preliminary applications are described.