There has been a lingering debate on the relationship between public managers’ professional socialization and their acceptance of citizen participation. In this paper, it is empirically confirmed that association participation strengthens municipal managers’ predispositions toward engaging citizens. It is found that municipal managers that are active in generalist-oriented professional associations will be more likely to realize successful practices for citizen engagement in peer municipalities, which boosts their perceived sense of citizen contribution, and reduces their perceptions on the costliness of engaging citizens. These relationships are found to be mediated by municipal managers’ technocratic orientation and engagement self-efficacy.