Importance: High-quality evidence on how to improve palliative care in nursing homes is lacking. Objective: To investigate the effect of the Palliative Care for Older People (PACE) Steps to Success Program on resident and staff outcomes. Design, Setting, and Participants: A cluster-randomized clinical trial (2015-2017) in 78 nursing homes in 7 countries comparing PACE Steps to Success Program (intervention) with usual care (control). Randomization was stratified by country and median number of beds in each country in a 1:1 ratio. Interventions: The PACE Steps to Success Program is a multicomponent intervention to integrate basic nonspecialist palliative care in nursing homes. Using a train-the-trainer approach, an external trainer supports staff in nursing homes to introduce a palliative care approach over the course of 1 year following a 6-steps program. The steps are (1) advance care planning with residents and family, (2) assessment, care planning, and review of needs and problems, (3) coordination of care via monthly multidisciplinary review meetings, (4) delivery of high-quality care focusing on pain and depression, (5) care in the last days of life, and (6) care after death. Main Outcomes and Measures: The primary resident outcome was comfort in the last week of life measured after death by staff using the End-of-Life in Dementia Scale Comfort Assessment While Dying (EOLD-CAD; range, 14-42). The primary staff outcome was knowledge of palliative care reported by staff using the Palliative Care Survey (PCS; range, 0-1). Results: Concerning deceased residents, we collected 551 of 610 questionnaires from staff at baseline and 984 of 1178 postintervention in 37 intervention and 36 control homes. Mean (SD) age at time of death ranged between 85.22 (9.13) and 85.91 (8.57) years, and between 60.6% (160/264) and 70.6% (190/269) of residents were women across the different groups. Residents' comfort in the last week of life did not differ between intervention and control groups (baseline-adjusted mean difference, -0.55; 95% CI, -1.71 to 0.61; P =.35). Concerning staff, we collected 2680 of 3638 questionnaires at baseline and 2437 of 3510 postintervention in 37 intervention and 38 control homes. Mean (SD) age of staff ranged between 42.3 (12.1) and 44.1 (11.7) years, and between 87.2% (1092/1253) and 89% (1224/1375) of staff were women across the different groups. Staff in the intervention group had statistically significantly better knowledge of palliative care than staff in the control group, but the clinical difference was minimal (baseline-adjusted mean difference, 0.04; 95% CI, 0.02-0.05; P <.001). Data analyses began on April 20, 2018. Conclusions and Relevance: Residents' comfort in the last week of life did not improve after introducing the PACE Steps to Success Program. Improvements in staff knowledge of palliative care were clinically not important. Trial Registration: ISRCTN Identifier: ISRCTN14741671.