This study investigated the degree that social interdependence predicted the achievement of 26 cooperative learning groups. Social interdependence was assessed in terms of postgraduate students' individual orientation (that is, cooperative, competitive, and individualistic). Participants were 84 postgraduate students enrolled in an introductory-level education research methodology course. An all possible subsets multiple regression was used to identify a combination of social interdependence variables that predict achievement. Results indicate that postgraduate students' levels of individualism predict achievement in a research methodology course. Specifically, groups consisting of students with the greatest individualistic orientation tend to produce the article critiques receiving a high evaluation, regardless of how heterogeneous the group is with respect to levels of individualism. This finding adds validity to the theories of active and cooperative learning and to the incremental support towards using cooperative learning groups to promote postgraduate students' active learning in research methodology courses.