Administrators of mental health services may expect evidence-based practice (EBP) to offer strategic benefits. Existing theory suggests that the benefits of implementing EBP vary by organizational characteristics. This paper presents a conceptual framework for considering how implementation impacts organizational performance. The framework is developed as a system dynamics simulation model based on existing literature, organizational theory, and key informant interviews with mental health services administrators and clinical directors. Results from the simulations show how gains in performance depended on organizations' initial inertia and initial efficiency and that only the most efficient organizations may see benefits in organizational performance from implementing EBP. Implications for administrators, policy makers, and services researchers are discussed.