Background The best protocol for cardiovascular preparticipation screening (PPS) in young athletes is uncertain. Objective The purpose of this study was to determine the value of integrating electrocardiographic (ECG) testing with standard history and physical examination during PPS to identify potentially serious cardiovascular abnormalities in young athletes. Methods A total of 2017 high school athletes seeking clearance for competitive sports were prospectively evaluated using a standardized history and physical examination, 12-lead ECG, and two-dimensional echocardiogram (echo). Primary outcome measures included the identification of cardiac disorders associated with sudden cardiac death. Secondary outcome measures included identification of abnormal, but nonlethal, cardiac conditions that required medical follow-up. Results Of these athletes, 14.7% had an abnormal history or physical examination and 3.1% had an abnormal ECG based on modern ECG interpretation criteria. Five primary outcomes (1 hypertrophic cardiomyopathy, 4 Wolff-Parkinson-White syndrome) and four secondary outcomes were identified. History and physical examination detected 40% of primary and 50% of secondary abnormalities. ECG detected all five primary abnormalities but none of the secondary abnormalities. Echo was abnormal in 1.2% and detected one primary and four secondary abnormalities. The false-positive rates for primary and secondary outcomes for history and physical examination and ECG were 14.5% and 2.8%, respectively. Conclusion ECG adds value to PPS through increased detection of arrhythmogenic and structural cardiovascular conditions associated with sudden cardiac death. Use of modern ECG interpretation standards allows a low false-positive rate. Routine echo may detect other clinically important cardiac abnormalities, but its role in PPS remains uncertain. © 2014 Heart Rhythm Society.