Community coalitions have been promoted as a strategy to help overcome challenges to the dissemination and implementation of evidence-based prevention programs. This paper explores the characteristics of coalitions that enable the provision of implementation support for prevention programs in general and for the implementation of evidence-based prevention programs with fidelity. Longitudinal cross-lagged panel models were used to study 74 Communities That Care (CTC) coalitions in Pennsylvania. These analyses provide evidence of a unidirectional influence of coalition functioning on the provision of implementation support. Coalition member knowledge of the CTC model best predicted the coalition's provision of support for evidence-based program implementation with fidelity. Implications for developing and testing innovative methods for delivering training and technical assistance to enhance coalition member knowledge are discussed.