Purpose: The purpose of this article was to evaluate the validity of the Progressive Aerobic Cardiovascular and Endurance Run (PACER) test in a sample of Hungarian youth. Method: Approximately 500 participants (aged 10-18 years old) were randomly selected across Hungary to complete both laboratory (maximal treadmill protocol) and field assessments (PACER) of aerobic capacity. Agreement between lab- and PACER-derived peak oxygen consumption (VO[subscript 2]) was examined using linear regression and 2-sided equivalence testing techniques, respectively. The impact of agreement on the classification accuracy of peak VO[subscript 2] estimates into FITNESSGRAM® fitness zones was determined with kappa statistics. Results: The final sample resulted in a total of 167 boys and 143 girls (N = 310). Analyses revealed that lab and PACER VO[subscript 2] shared 13% to 18% of their variance (R[superscript 2][subscript boys] = 0.13, R[superscript 2][subscript girls] = 0.18) and that limits of agreement ranged from -39.9 mL/kg/min to +37.6 mL/kg/min depending on the sex. The absolute error values were 14% for boys and 16% for girls; however, the average peak VO[subscript 2] estimates from the PACER were within the 10% equivalence region for girls (37.2 mL/kg/min to 45.4 mL/kg/min), but not for boys (45.2 mL/kg/min to 55.2 mL/kg/min). When lab and PACER VO[subscript 2] were categorized according to Fitnessgram zones, agreement was fair for both sexes (boys, Kappa = 0.25, and girls, Kappa = 0.31). Conclusions: Although the correlations between measured and predicted peak VO[subscript 2] were lower than expected, the magnitude of error observed in the PACER is similar to past ranges of error observed in other studies (10%-15%), but the large individual error should be considered when interpreting individual results from this field-based measure of aerobic capacity. There was reasonable classification agreement between lab estimates and the PACER test for classification into the various fitness standards.