Participation by first responders, especially police officers, is essential for the successful implementation of deflection and pre-arrest diversion programs. Effective officer buy-in increases the number of referrals to the program, enhances relations between police and community members, creates or enhances cross-sector collaboration to create new pathways to community-based behavioral health services, and provides the opportunity to increase equity in the provision of treatment and other resources to communities of color and other underserved communities. Different types of deflection programs, whether led by law enforcement agencies or administered by other types of organizations (e.g., prosecutors, behavioral health, nonprofit, etc.) share many of the same obstacles to securing officer support, but they also have their own unique barriers. This checklist offers evidence-based strategies to enhance officer buy-in for deflection programs resulting in better outcomes for individuals, agencies, and communities.