Producer organizations are often said to have the potential to help farmers meet the increasing quality requirements of agricultural value chains. However, the external environment may influence producer organizations' room for maneuver in implementing effective quality management. This article assesses the influence of the relations between producer organizations, producers and other actors in the value chain on the capacity of producer organizations to implement quality management. Our analysis focuses on four Moroccan milk collection cooperatives that started using a milk analyzer with the aim of eliminating cheating by their suppliers. The cooperatives' room for maneuver in improving quality management was limited by the presence of competitors for milk collection and by the agro-industry's lack of transparency in the way its own quality controls were applied. Future studies on how producer organizations can meet the quality challenge should include the strategies of other actors in the value chain in their analyses. (Résumé d'auteur)