This study will enroll individuals with PAD who have been referred by their doctor for a coronary angiogram to confirm the presence of CAD. A control group composed of individuals who do not have PAD, but have similar risk factors for atherosclerosis, will also be enrolled. All participants will attend one study visit. They will undergo a coronary angiogram, a procedure in which a special dye is inserted intravenously into an artery of the heart. X-rays will be taken to document how blood flows through the artery. Questionnaires assessing quality of life, exercise habits, tobacco exposure, and family medical history will be completed. Participants will also undergo blood pressure measurements and blood collection for genetic analysis. Yearly follow-up phone calls will occur for 5 years to document any hospitalizations.