The present study focuses on the use of a cooperative methodology with university students during the last year of their degree programme. The task structure could be freely chosen, and there were no restraints on group decisions to deal with the classroom work. All the elements of cooperation were based on a reward structure. The results show that internal group cohesion can be achieved through an inter-group competitive reward system and positive interdependence can be reached with an extreme cooperative reward structure, grounded on individual assessments of the students. The results also point to the importance of a reward structure, based on grades, when using a cooperative methodology in the university classroom. (Contains 1 figure.)