Testing and Exploring the Limits of Traditional Notions of Fidelity and Adaptation in Implementation of Preventive Interventions.

This commentary reflects on key challenges raised across the articles of this special issue, notably the tension between fidelity and adaptation, the importance of articulating core components and principles of evidence-based programs, the need for pragmatic measures, and the challenges associated with articulating and testing mechanisms of implementation strategies. These challenges are amplified in the context of prevention research where task shifting, or revising professional roles, is especially common. Synergies with work emerging from the Society for Implementation Research Collaboration are highlighted throughout.