Scholars in theology, philosophy, history, political science, and anthropology have long recognized the importance of dehumanization in both triggering and sustaining genocide. Few of these scholars have, however, looked to the mounting empirical research on this topic. This is unfortunate. The sciences can help move us beyond a description of dehumanization -- unquestioned -- to a set of predictions concerning when it will arise, which kinds of people are most likely to lead the charge and which are most likely to follow like bleating sheep.