Agricultural cooperatives evolve in a context with complexity and changes of their legal, social and business environment. Strategic management could be a relevant approach to help cooperative members to improve the global performance and the social responsibility of their cooperatives. To formalize and to manage their strategy, we propose as an accompaniment a method entitled PerfCuma. The theoretical framework is based on the concept of systemic approach to change. The method is organized in four steps: i) an in-depth stakeholder’s analysis of the cooperative situation (including sustainability) and the cooperative goals; ii) formalizing the strategy by defining strategic lines. We use the cognitive map approach to model the complexity to understand the strong drivers of the strategy; iii) drawing up the balanced scorecard and an action plan to manage the strategy; iv) monitoring the implementation of the strategy. A test of the method on five Cooperatives for the Use of Agricultural Equipment (Cuma) has been successful. The method is now unfolded in France.