The increasing numbers of children and adolescents with elevated blood pressure (BP) and overweight continue to be important public health problems. Data for this study were taken from a longitudinal pediatric cohort study based on electronic medical record (EMR) data of children (3–11 year) and adolescents (12–17 year) (total n = 244 523) from three large US health plans over the calendar period 1/1/07 to 12/31/09. Age-eligible subjects entered the cohort at the time of the first clinic visit in which blood pressure (BP) height, and weight were measured. Body mass index (BMI) percentiles were calculated using height, weight, gender, and age, based on the CDC-established reference growth charts, and BP percentiles were gender, age- and height-specific, based on NHBPEP (Working Group) normative values. We report here BMI percentile and BP percentile measures collected at the first eligible clinic visit, based on single measures. At entry, 58.3% of subjects were 3–11 years of age, 41.7% were 12–17 years, 50.1% were female. As noted in the table, levels of overweight were high in all age categories, beginning at age 3, with similar percentages through age 17. These data suggest that efforts to prevent overweight and obesity need to target children at a very young age. Given the cross-sectional stability of the data, we speculate that excess weight and elevated BP have early onset and persist over time. Further analyses will evaluate tracking of BMI and BP percentile over time, and elucidate the impact of BMI on BP status.