Objective: Within the context of self-determination theory, individuals vary in the extent to which they are oriented toward autonomy and control. Previous research on the relationship between motivational orientations and drinking behavior among college students has suggested that students who are more autonomously oriented consume less alcohol whereas those who are more control oriented consume more alcohol. This research evaluated the extent to which these relationships are mediated by the perceived approval of friends and parents, both of which are important sources of potential influence on the behavior of college students. Method: First-year students (N = 818, 58% female) who reported one or more heavy drinking episodes in the previous month completed online assessments of their drinking behavior, autonomous and controlled orientations, and perceptions of the approval of drinking (injunctive norms) by important others (friends and parents). Results: The results suggested that controlled orientation was associated with greater alcohol use and that this association was mediated by perceptions of friends being more approving of problematic drinking. In contrast, autonomous orientation was associated with less alcohol use and this association was mediated by perceptions of friends being less supportive of problematic drinking. No support was found for perceptions of parents' approval as a mediator of the associations between either orientation and drinking. Conclusions: The findings highlight the importance of perceptions of friends' approval or disapproval of problematic drinking in understanding the relationship between self-determination and heavy drinking among college students.