Both police officers and corrections officers perform work that brings them into contact with behaviors and situations that have the potential to seriously injure or kill them, and they are often exposed to the suffering and deaths of others, some of whom they are charged with protecting. This precipitates mental and physical stress that threatens their mental and physical health. Although NIJ has a long history of supporting research related to stress for law enforcement personnel, in 2016 NIJ determined that a coordinated research agenda was needed to better respond to this long-standing issue. As a result, NIJ developed the Safety, Health, and Wellness Strategic Research Plan. This plan specifies current and projected efforts to promote the safety, health, and wellness of those who work in or are affected by the criminal justice system. The uniqueness of the plan is its call for science-based tools that measure and monitor physical and mental health. The plan, which will continue through 2021, focuses on all personnel who are employed by, under the supervision of, or interact with the criminal justice system. This article summarizes some of the early studies funded by NIJ under this plan. The overall goal of this research is to translate research findings into an evidence-based strategy that will counter the threats to criminal justice personnel safety and health posed by the stress of the work they perform.