Since 2011, the COPS Office and the Bureau of Justice Assistance (BJA) have raised awareness, increased knowledge, and promoted practices that support the safety and well-being of law enforcement officers through the Officer Safety and Wellness (OSW) Group. In October 2016, the OSW Group brought law enforcement practitioners and subject matter experts together to discuss promising practices for supporting officer resilience. Resilience - the ability not only to recover emotionally from traumatic events but to withstand day-to-day work-related stress - is critical to the physical and psychological health of all law enforcement officers. In addition to summarizing the group's discussions at the October meeting, this report contains case studies of the emotional impact of mass casualty events on first responders in Dallas, Texas; Orlando, Florida; and San Bernardino, California. The report also provides recommendations for preparing officers for traumatic events and strategies for supporting overall resilience through physical and emotional health.