Teaching-learning based on cooperative learning is grounded on a methodology that is currently one of the most widely used within formal education classrooms. Recently, special attention has begun to be paid to a fundamentally relevant aspect of the assessment of the learning of university students within their group performance: their individual grades obtained from teamwork. In addition to describing the individual grading system that is used to assess individual contributions, this study analyses the perceptions of 99 university students regarding the benefits that the system has for students' learning process. A system of evaluation based on self-assessment, co-assessment and peer-assessment was implemented in a Spanish university. The results collected using a specially designed questionnaire led to the conclusion that improvements were achieved in the teaching-learning process, in manifesting positive attitudes and in improving students' ability to learn to learn. In conclusion, students feel that they are granted greater control over their final grade and, as a result, perceive that their involvement in the task increases and their capacity for self-criticism develops.