Background Clinicians often use physical performance tests (PPT) to measure performance measures in sports since they are easy to administer, portable, and cost-efficient. However, PPT often lack good or known psychometric properties. Perhaps, the 30-second chair-stand test (30CST) would be a good functional test in athletic populations as it has been shown to demonstrate good psychometric properties in older adults. Hypothesis/Purpose The purpose of this study was to determine normative values for and concurrent, convergent and discriminative validity of 30CST for healthy young adults aged 19-35 years. Study Design Cross-sectional Methods Eighty-one participants completed this study. All participants performed two trials of 30CST, 5-times sit-to-stand (5xSTS), and lateral step-up test (LSUT). Investigators used the International Physical Activity Questionnaire Leisure Domain (LD-IPAQ) to divide participants into insufficiently or sufficiently active groups based on the weekly metabolic equivalent of task per the Physical Activity Guidelines for Americans. Results Participants (Mean + SD age, 25.1 ± 3.4 years; body height, 1.71 ± 0.09 m; body mass, 72.6 ± 16.1 kg; females 47) performed an average of 33.0±5.4 30CST repetitions. The 30CST performance was negatively associated with 5xSTS (r=-0.79 p=0.01) and positively associated with LSUT performances (r=0.51, p=0.01) when using Pearson correlations. In addition, the sufficiently active group performed significantly greater 30CST repetitions than the insufficiently active group (mean difference = 2.5; p=0.04). Conclusions In addition to finding a reference value for 30CST performance in young adults, investigators found that the 30CST displayed concurrent and convergent validity in assessing functional lower extremity (LE) muscle strength and discriminated between those with sufficient and insufficient physical activity levels. Training and rehabilitation professionals could use the 30CST for testing functional LE muscle strength for athletes in pre-season or during rehabilitation. Future investigators should perform studies to determine if 30CST predicts sport performance. Level of Evidence Level 2.