Objective: Hematopoietic stem cell transplant (HSCT) survivors who are 1 to 3 years posttransplant are challenged by the need to resume valued social roles and activities--a task that may be complicated by enduring transplant-related psychological distress common in this patient population. The present study investigated whether transplant survivors who receive adequate social support from their spouse or intimate partner experience lower distress. Method: Effects of receiving a greater quantity of partner support (a common approach to studying enacted support) were compared with effects of receiving more effective partner support (i.e., support that more closely matches their needs in terms of its quantity and quality). Men and women (N = 230) who were 1 to 3 years posttransplant completed measures of partner support quantity (Manne & Schnoll, 2001), partner social support effectiveness (Rini & Dunkel Schetter, 2010), and psychological distress (Brief Symptom Inventory; Derogatis & Spencer, 1982). Potential medical and sociodemographic confounds were controlled in analyses. Results: As hypothesized, survivors reported less distress when they received more effective partner support (p less than 0.001). Quantity of partner support was not associated with distress (p = 0.23). An interaction revealed that when partner support was effective, the quantity of support survivors received was not associated with their distress (p = 0.90); however, when partner support was ineffective, receiving a greater quantity of partner support was associated with substantially elevated distress (p = 0.002). Conclusions: Findings suggest that clinical approaches to addressing or preventing enduring distress after HSCT should target features of partner support related to its appraised effectiveness. (Contains 3 tables and 1 figure.)