Nordic Combined (NC) and Ski Jumping (SJ) require particular athletic abilities and physical attributes for optimal performance. For instance, SJ requires particular focus on jumping technique and explosiveness, whereas the cross country ski portion of NC involves aerobic energy delivery, skiing efficiency, and power generation. Coaches and athletes monitor various performance metrics throughout the year to determine response to training and, hopefully, predict future performance. Normative data for these metrics has been analyzed in elite SJ and NC athletes but there is limited information regarding junior athletes. PURPOSE: Present normative biometric and performance testing data of American junior NC and SJ athletes and compare differences between age and sex. METHODS: A retrospective cohort study was completed evaluating data collected on 299 NC and SJ athletes ages 7-19 tested as part of USA Nordic's normal preseason evaluations between 2012-2018. Body mass index, static standing jump and countermovement jump height, various broad jump distances, timed agility testing, and 20 meter sprint times were collected and analyzed for differences between age and sex. RESULTS: Body mass index was greater in females than males. The interaction between age and sex was significant for static jump height, all broad jump metrics, time agility testing, and 20 meter sprint time. Jump power was greater in females than males. No difference was found between sex or across age in countermovement jump height. CONCLUSIONS: This was the first study to report biometric and performance data in junior American NC and SJ athletes. Our findings provide valuable normative information and identified several age and sex related differences in these athletes. These findings can be used by other junior athletes and their coaches for comparison purposes and when developing training programs.