There is a substantial gap in knowledge of the practical application of comprehensive "best practice" public policies and how these policies are actually implemented. This research examines implementation of a comprehensive best practices gang reduction policy across three cities. Action research case study methodology shows that explanations for diverse implementation arose from each city’s ecological constitution, which is a necessary antecedent to categorization according to Matland’s policy implementation typology. This study affirms the use of an ecological perspective and supports the use of Matland’s typology in a collaborative and comparative public policy context.