Healthy People 2020 (HP 2020), released in December 2010, outlines numerous public health objectives, including objectives for youth physical activity participation.1 HP 2020 includes three objectives for meeting current federal physical activity guidelines for (1) aerobic physical activity (participation in ≥60 minutes of aerobic activity per day, 7 days per week) (PA 3.1); (2) muscle-strengthening activity (muscle-strengthening activities on ≥3 days per week) (PA 3.2); and (3) aerobic physical activity and muscle-strengthening activity combined (PA 3.3).1,s The HP 2020 target for PA 3.1 is 20.2%; targets for PA 3.2 and PA 3.3 are not set because baseline data are not available. To meet the HP 2020 targets for physical activity, promotion of physical activity among female high school students,3 high school students in upper grades,3 and youths with obesity4 might be warranted, given that these subpopulations are at risk for low levels of physical activity. To determine the proportion of U.S. youths who meet these HP 2020 objectives, CDC analyzed data from the 2010 National Youth Physical Activity and Nutrition Study (NYPANS), a school-based study conducted by CDC that included height and weight measurements and a survey that measured physical activity and dietary behaviors among a nationally representative sample of students in grades 9-12. This report summarizes the results of that analysis, which indicated that among students nationwide in grades 9-12, 15.3% met the aerobic objective, 51.0% met the muscle-strengthening objective, and 12.2% met the objective for both aerobic and muscle-strengthening activities. To improve youth physical activity participation, efforts are needed among CDC, state and local public health agencies, schools, and other public health partners that promote physical activity.