Abstract: Health dysfunction and poor interpersonal connectedness are consistent risk factors for veteran suicide; however, to the extent that veterans adhere to treatment recommendations, such outcomes may be mitigated. Our sample of United States veterans completed measures of treatment adherence, somatic health, interpersonal connectedness, and suicide risk. Serial mediation analyses assessing the link between treatment adherence and suicide risk, and the mediating impact of somatic health and connectedness, were conducted. Greater adherence was associated with better somatic health and, in turn, to less thwarted belongingness and perceived burdensomeness and, finally, to less suicide risk. Treatment adherence remained related to less burdensomeness and, in turn, to less suicide risk, after covarying depression. Treatment adherence appears to have beneficial downstream effects on somatic health and interpersonal functioning. Healthcare strategies promoting efficacy and activation, and addressing socioenvironmental and systemic barriers to adherence, may improve standard of care, facilitate engagement in health promotion behaviors, fulfill interpersonal needs, and reduce suicide risk.