BACKGROUND Surrogate decision makers for incapacitated, critically ill patients often struggle with decisions related to goals of care. Such decisions cause psychological distress in surrogates and may lead to treatment that does not align with patients' preferences. METHODS We conducted a stepped-wedge, cluster-randomized trial involving patients with a high risk of death and their surrogates in five intensive care units (ICUs) to compare a multicomponent family-support intervention delivered by the interprofessional ICU team with usual care. The primary outcome was the surrogates' mean score on the Hospital Anxiety and Depression Scale (HADS) at 6 months (scores range from 0 to 42, with higher scores indicating worse symptoms). Prespecified secondary outcomes were the surrogates' mean scores on the Impact of Event Scale (IES; scores range from 0 to 88, with higher scores indicating worse symptoms), the Quality of Communication (QOC) scale (scores range from 0 to 100, with higher scores indicating better clinician-family communication), and a modified Patient Perception of Patient Centeredness (PPPC) scale (scores range from 1 to 4, with lower scores indicating more patient-and family-centered care), as well as the mean length of ICU stay. RESULTS A total of 1420 patients were enrolled in the trial. There was no significant difference between the intervention group and the control group in the surrogates' mean HADS score at 6 months (11.7 and 12.0, respectively; beta coefficient, -0.34; 95% confidence interval [CI], -1.67 to 0.99; P = 0.61) or mean IES score (21.2 and 20.3; beta coefficient, 0.90; 95% CI, -1.66 to 3.47; P = 0.49). The surrogates' mean QOC score was better in the intervention group than in the control group (69.1 vs. 62.7; beta coefficient, 6.39; 95% CI, 2.57 to 10.20; P = 0.001), as was the mean modified PPPC score (1.7 vs. 1.8; beta coefficient, -0.15; 95% CI, -0.26 to -0.04; P = 0.006). The mean length of stay in the ICU was shorter in the intervention group than in the control group (6.7 days vs. 7.4 days; incidence rate ratio, 0.90; 95% CI, 0.81 to 1.00; P = 0.045), a finding mediated by the shortened mean length of stay in the ICU among patients who died (4.4 days vs. 6.8 days; incidence rate ratio, 0.64; 95% CI, 0.52 to 0.78; P<0.001). CONCLUSIONS Among critically ill patients and their surrogates, a family-support intervention delivered by the interprofessional ICU team did not significantly affect the surrogates' burden of psychological symptoms, but the surrogates' ratings of the quality of communication and the patient-and family-centeredness of care were better and the length of stay in the ICU was shorter with the intervention than with usual care.