This paper takes on a different address to youth fitness testing from previous literature by applying a cross-cultural comparison of youth fitness testing in both the US and China. Utilizing a modified version of Bronfenbrenner's Ecological Model, the chronosystem (historical evolution over time), and macrosystem (social and cultural vantage point) factors, in particular, are explored within the realm of youth fitness testing. From the lens of this model changes and characteristics of youth fitness testing practice are identified. It is concluded that both fitness testing batteries were revised periodically as time passes, even though more revisions and debates occurred in the US. Although both countries made the shift from skill-related fitness to health-related fitness, social and cultural values in both countries dictated the implementation styles of youth fitness testing and the use of the current youth fitness testing results. Future theoretical research on youth fitness testing should investigate the other three factors of the model.