Increasing the quantity and quality of school site physical activity, specifically physical education, has become a primary emphasis area for the nation’s health promotion initiative (CDC, 1997; USDHHS/USDE, 2000). However, large scale physical activity surveillance has been problematic in the elementary age population. Therefore, the objective of this study was to empirically determine a valid criterion-referenced pedometer step intensity (STINT) standard for quantifying the lesson time first- and second-grade physical education students spend in moderate to vigorous physical activity (MVPA). The one-third holdout technique was used to randomly assign participants to the validation (N=246) and cross-validation (N=123) samples. Using the criterion test model, optimal STINT cut off scores were empirically and judgmentally determined from the validation sample and further examined on the cross-validation sample. Systematic observation (i.e., 33% MVPA), heart rate telemetry (i.e., 50% moderate to vigorous heart rate), and a standardized z-score of the two measures were the criterion physical activity assessment techniques. Pedometry was the predictor assessment technique. Data were collected from 45 thirty-minute chasing, fleeing, and dodging lessons implemented in six schools. The three step analytic procedure of mastery/nonmastery outcome probabilities (i.e., c > .80), phi coefficients (i.e., higher scores were desirable), and error proportions (i.e., Type II < Type I) were used to determine the optimal STINT score for accurately quantifying 33% MVPA within a 30-minute physical education class. Pearson r coefficients were computed between each of the physical activity measures for both samples, genders, and grades. STINT was highly correlated with observation (r=.74 to .86, p < .001), and moderately correlated with heart rate (r=.43 to .62, p < .01). Observation and heart rate data demonstrated a low to moderate (r=.36 to .53, p < .01) relationship. Systematic observation was selected as the criterion measure from which to establish STINT cut off scores. Five STINT scores found to be valid indicators of 33% MVPA in the validation sample were valid indicators of STINT in the cross-validation sample. The optimal STINT cut score ranged from 60 to 63, which is equivalent to 1800 to 1890 pedometer counts in a 30-minute physical education class. In conclusion, these data support the use of pedometry STINT values as a valid indicator of MVPA time. Pedometry demonstrates promise as a viable surveillance instrument for measuring MVPA in elementary school physical education.