Thirty-day heart failure readmissions can be reduced if multiple interventions, such as 7-day postdischarge follow-up, are implemented, but this task is challenging for health systems. Ten hospitals participated in a multisystem collaborative implementing evidence-based strategies. The overall 30-day readmission rate was reduced more in the collaborating hospitals than in the noncollaborating hospitals (from 29.32% to 27.66% vs from 27.66% to 26.03%, P = .008). Regional collaboration between health care systems within a quality improvement project was associated with reduced 30-day readmission.