This study will examine ECGs and other study data from participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study. As ECG abnormalities typically begin to develop in young adults, the CARDIA participants will provide researchers with an excellent study population. As part of the CARDIA study, ECGs were obtained from participants at baseline, and Years 7 and 20. Study researchers will use state-of-the-art technology and standardized Minnesota Code and Novacode methods to electronically code participants' ECGs and accomplish the following: 1) assess the frequency of ECG abnormalities in young adults of different races; 2) examine potential risk factors for the development and progression of ECG abnormalities; 3) investigate the relationship between ECG abnormalities and other measures of heart disease; and 4) assess differences in the frequency and patterns of ECG abnormalities between different racial groups. Study researchers will also analyze additional CARDIA study data, including cardiovascular disease risk factors, measures of atherosclerosis, and echocardiographic ultrasound pictures of the heart.