Definitions set the parameters of research and influence the results and conclusions. It is thus crucial that researchers critically examine definitions and terms, particularly in fields that use popular terms likely to be influenced by the unacknowledged biases and political concerns of the dominant group. The study of sexual assault is such a field, and therefore this article examines researchers' definitions of sexual assault, rape, and related terms. Definitions vary along several dimensions, including (a) the sexual behaviors specified, (b) the criteria for establishing nonconsent, (c) the individuals specified, and (d) the perspective specified—that is, who decides whether sexual assault has occurred. For each dimension, the article discusses implications for researchers' results and conclusions, underlying assumptions, and political ramification