This REU site proposal will train ten students in research methods and theory of Primate Social Ecology on Totogochillo Island, Lake Catemaco, Mexico. During the summer, students will take a 30 day course in which they will conduct directed and individual research projects on the free-ranging colony of stumptail macaques (Macaca arctoides). One hour lectures will be given every evening on topics to help students design their projects, collect data, analyze those data, and interpret their results within a scientific framework. Initial statistical analyses of the data, a preliminary paper and an oral report will be completed at the end of the course. During the following academic year, students will take independent study courses at their college or university in which they will analyze and write up the results of their research with the senior faculty member. The students will submit a paper describing the results of their project to a refereed scientific journal.