Suicide risk is elevated among psychiatric inpatients; however, research has not examined moderators of the associations between perceived social support and thwarted belongingness (TB) and perceived burdensomeness (PB), such as involvement with criminal associates. Adult psychiatric inpatients (N = 142) completed assessments. Perceived social support was negatively associated with TB and PB; however, associates’ criminal involvement did not moderate these associations. A significant interaction indicated a stronger negative association between perceived social support and TB when participants spent more time with associates. Therefore, time spent with associates, regardless of criminal involvement, may be a relevant interpersonal suicide risk factor.