Background: People in reentry from prison or jail (returning citizens) living with HIV and substance use problems often experience numerous stressors and are at high risk for resumed substance use. Interventions are needed to manage stress as a pathway to reduced substance use. Objective: This study explored the effect of a hatha yoga intervention as compared to treatment as usual on stress and substance use among returning citizens living with HIV and substance use problems. Methods: Participants were randomized to either a 12-session, 90-minute weekly yoga intervention or treatment as usual. All participants were clients of a service provider for returning citizens that offered case management, health care, and educational classes. Outcomes included stress as measured by the Perceived Stress Scale at the completion of the yoga intervention (three-months) and substance use as measured by the Timeline Followback at one-month, two-months, and three-months. Results: Seventy-five people were enrolled, two of whom were withdrawn from the study because they did not have HIV. Of the 73 remaining participants, 85% participated in the three-month assessment. At three-months, yoga participants reported less stress than participants in treatment as usual [F (1,59) = 9.24, p<.05]. Yoga participants reported less substance use than participants in treatment as usual at one-month, two-months, and three-months (X-2 (1) = 11.13, p<.001]. Conclusion: Yoga interventions for returning citizens living with HIV and substance use problems may reduce stress and substance use. This finding is tentative because the control group did not receive an intervention of equal time and intensity.