Long-term maintenance of behavioral change to reduce health risk factors is essential to producing a positive effect on medical outcomes. This study examines whether an ongoing, long-term relationship can be used to help patients diagnosed with coronary artery disease adhere to a risk-reducing behavioral intervention and maintain healthy behavioral changes. One hundred and sixty patients with diagnosed coronary artery disease will be randomized to a standard behavioral treatment group or to a standard behavioral treatment group including a couples intervention and followed for 18 months. The treatment in both groups follows tenets of cognitive behavioral and Self-Determination Theories as well as the Transtheoretical Model of Behavior Change. In addition, the couples intervention is designed to (1) change the patient's environment to facilitate cardiac risk-reducing behavioral changes, (2) optimize social reinforcement and motivation for behavior change, and (3) decrease relationship stress. Behavioral outcomes assessed include adherence to an exercise regimen, adherence to dietary recommendations and adherence to lipid-lowering medication. Lipid values, psychological variables and relationship variables are assessed throughout the study and at follow-up. While we expect both groups of cardiac patients to successfully adapt new health behaviors, we expect the couples intervention to be superior in helping maintain long-term health behaviors.