Background— The American Heart Association recently developed definitions and metrics for monitoring the spectrum of cardiovascular health in adolescents and children. Current nationally representative prevalence estimates according to sex and race/ethnicity are unavailable. Methods and Results— We examined the components of cardiovascular health in 4673 participants aged 12 to 19 years (representing ≈33.2 million US adolescents) from the 2005–2010 National Health and Nutrition Examination Surveys. Population prevalence of individual cardiovascular health behaviors and factors was estimated according to American Heart Association criteria for poor, intermediate, and ideal levels. Ideal blood pressure was most prevalent (males, 78%; females, 90%), whereas a dramatically low prevalence of ideal Healthy Diet Score was observed (males, <1%; females, <1%). Females exhibited a lower prevalence of ideal total cholesterol (65% versus 72%, respectively) and ideal physical activity levels (44% versus 67%, respectively) yet a higher prevalence of ideal blood glucose (89% versus 74%, respectively) compared with males. Approximately two thirds of adolescents exhibited ideal body mass index (males, 66%; females, 67%) and ideal smoking status (males, 66%; females, 70%). Less than 50% of adolescents exhibited ≥5 ideal cardiovascular health components (45%, males; 50%, females). Prevalence estimates according to sex were consistent across race/ethnic groups. Conclusions— The low prevalence of ideal cardiovascular health behaviors in US adolescents, particularly physical activity and dietary intake, will likely contribute to a worsening prevalence of obesity, hypertension, hypercholesterolemia, and dysglycemia as the current US adolescent population reaches adulthood. Population-wide emphasis on establishment of ideal cardiovascular health behaviors early in life is essential for maintenance of ideal cardiovascular health throughout the lifespan.