This study addressed the question of how to structure coalitions in order to increase their engagement in multiple strategies for health promotion and consequently to improve their effectiveness. Three structural variables were chosen: (i) coalition's heterogeneity, captured by the professional diversity of its members; (ii) coalition's configuration, defined as the way members were involved in the coalition: full- or part-cycle membership, full- or part-time assignment, and core or peripheral membership; and (iii) coalition's contractual collaborations with external professionals. A large non-profit network of community centers served as the setting for this study. The sample consisted of 37 coordinators of local coalitions for health promotion in Israel. The study's design was a cross-sectional survey. Data were collected by a multimethod (semistructured interviews, self reported questionnaires and administrative data) approach. Effectiveness was assessed by a self-report questionnaire administrated to coalition coordinators. Engagements in multistrategies as well as structural variables were measured by semistructured interviews with coalition coordinators. Results demonstrated that while a homogeneous, bounded structure seemed to promote the implementation of health education programs, a more flexible coalition configuration with frequent use of professionals contributed more to working by multiple strategies and improved coalition's effectiveness. In addition, the use of external professionals promoted action for a healthier environment, but did not add to empowering the community. The results contribute to shifting the conception of a coalition as a tightly bounded, well-defined, stable entity to that of a more fluid and permeable structure interacting with an external environment. These findings highlight the importance of incorporating structural considerations into the management of coalitions and are discussed in light of the potential costs and benefits of alternative modes of structuring such coalitions.