Abstract: The new century witnesses the “New Public Management Movement” moving towards “cooperative governance”, but cooperation itself does not run automatically. In the context of mandatory cooperation, the strategies adopted by weak sectors to establish internal legitimacy and promote sincere cooperation with strong sectors have not drawn sufficient attention according to current literature, hence a need of an in-depth exploration of the specific implementation. Therefore, the article adopts the relatively fragmented paths of political science and organizational management in collaborative governance research, and integrates the two independent paths of program and cognition into two different levels of understanding internal legitimacy, thus constructing a “program-cognition” analysis framework for weak sectors to establish internal legitimacy; the article further takes the inter-departmental cooperation of school sports facilities’ opening to the public in X city as a typical case, with an aim to explore the strategies adopted by weak sectors to gain internal legitimacy in promoting cooperation with strong sectors. The results indicate that vertical authoritative and social needs can bring strong external legitimacy to weak sectors, while the construction of internal legitimacy requires three stages of procedures: dialogue and participation, negotiation and commitment agreements, accompanied by the development of three cognitive levels of shared understanding, understanding and trust, and internal identification. The strategies that work well in the constraint scenario of “the weak collaborating with the strong” will have a broader scope for implementation under relaxed constraints or other supportive conditions.

Key words: public management, collaborative governance, legitimacy, program cognition, inter-departmental cooperation, weak sectors