This paper examines the mediating role of students' goals in group work at university. Research on cooperative and collaborative learning has provided empirical support for the cognitive, motivational and social benefits of group work but the antecedents of motivation and ongoing management of emerging motivational and socio-emotional issues have received less attention. A theory of self-regulation that incorporates students' personal goals and perceptions of context, combined with a sociocultural perspective on co-regulation of individuals and contexts, can help understand why and how some groups resolve their social challenges while others are less successful. An empirical study highlighted the mediating role of students' goals in their appraisals of group assignments, perceptions of various aspects of the contexts, and in turn regulation strategies to achieve their goals. Qualitative differences were found in the regulation strategies of students with positive and negative appraisals. (Contains 1 figure.)