Our goal was to identify barriers and facilitators to the implementation of evidence-based practices from the perspectives of multiple stakeholders in a large publicly funded mental health system. We completed 56 interviews with three stakeholder groups: treatment developers (n = 7), agency administrators (n = 33), and system leadership (n = 16). The three stakeholder groups converged on the importance of inner (e.g., agency competing resources and demands, therapist educational background) and outer context (e.g., funding) factors as barriers to implementation. Potential threats to implementation and sustainability included the fiscal landscape of community mental health clinics and an evolving workforce. Intervention characteristics were rarely endorsed as barriers. Inner context, outer context, and intervention characteristics were all seen as important facilitators. All stakeholders endorsed the importance of coordinated collaboration across stakeholder groups within the system to successfully implement evidence-based practices.