This article describes the administration of a heart rate variability (HRV) biofeedback intervention designed to reduce posttraumatic stress disorder (PTSD) severity in post-9/11 service members. The study recruited 33 male OEF/OIF/OND combat veterans in a Los Angeles transitional housing program. Twenty-seven veterans completed the study. Participants attended eight once-weekly HRV biofeedback group sessions. For the first four weeks, veterans learned to use biofeedback to regulate physiological stress responses. The latter four weeks consisted of real-life biofeedback application and coaching. Results suggest that consistent HRV biofeedback practice was essential for HRV improvement, which may help alleviate PTSD.