AbstractResearch summaryChanging police use of force policies and training to incorporate de‐escalation tactics is one of the most routinely recommended police reform measures. Despite widespread promotion and proliferation of de‐escalation trainings, to date, no research has empirically demonstrated that these trainings reduce use of force in the field (Engel, R. S., McManus, H. D., & Herold, T. D., 2020). Therefore, it is unknown if de‐escalation trainings actually reduce force, have no impact, or have unintended consequences that possibly increase injuries to officers or citizens. We collaborated with the Louisville Metro Police Department (LMPD) in 2019 to evaluate the impact of the Integrating Communications, Assessment, and Tactics (ICAT) de‐escalation training developed by the Police Executive Research Forum. Using a stepped‐wedge randomized controlled trial research design, the panel regression results demonstrated statistically significant reductions in use of force incidents (−28.1%), citizen injuries (−26.3%), and officer injuries (−36.0%) in the post‐training period. These significant reductions were larger than any changes in LMPD arrest patterns during the same period. Other possible time‐based confounders were also considered; the combined analyses show robust, consistent, and immediate impacts on use of force counts after training.Policy implicationsOur findings suggest that agencies should continue to implement and evaluate de‐escalation trainings and adopt other resiliency‐based approaches to police training. To facilitate long‐term changes in police behavior, a holistic approach is recommended that supports training tenets with complementary policies, supervisory oversight, managerial support, and community involvement in reform efforts. Finally, researchers must continue to support police executives willing to open their agencies for evaluation and oversight. Due to the LMPD's partnership with researchers, evidence now exists that de‐escalation training can make police encounters with the public safer for all. Continuing to implement and evaluate innovative police trainings is our best opportunity for meaningful changes in policing.