Biometric status, cardiovascular endurance, strength, speed, flexibility, and coordination were assessed in a cross-sectional survey involving 3,540 Swiss boys and girls, aged 9 to 19. Strength and endurance were better among boys, whereas girls displayed better flexibility. Most of the performances among girls did not change from 14 years onwards, while boys exhibited better performances after 15-16 years. The coefficients of correlation between the tests varied from as low as .16 (NS) to .63 (p <.01). Multiple regression analyses showed that height, weight, and chronological and biological age altogether were independently related to the performance on most of the tests. Fitness is a multidimensional concept that not only evolves with chronological age but also depends on biometrical characteristics such as pubertal stage, height, and weight.