Peer-group intervention can be successfully used to implement lifestyle changes and lower cardiovascular risk. In the Fifty-Fifty Program, 543 adults aged 25–50 years with at least one cardiovascular risk factor (hypertension, being overweight, smoking, or physical inactivity) were randomly assigned to receive peer-group-based intervention or to self-management for 12 months. The intervention consisted of monthly meetings involving role-play, brainstorming, and activities to address emotions, diet, and exercise. Peer-group intervention was associated with an improvement in a composite risk-factor score measuring blood pressure, exercise, weight, alimentation, and tobacco use. Long-term follow-up is ongoing.