Vertical jump (VJ) height is an important determinant of lower body power. Many tools are used to measure VJ, with the reach and touch technique (RTT) being the most common. Jump-related technology advances have created electronic contact mats (ECM) that use basic kinematic equations to calculate jump height based on flight time. PURPOSE: To assess the reliability and validity of VJ heights collected by ECM compared to RTT after different warm-up conditions. METHODS: A total of 34 participants (16 men, 18 women) performed three vertical jumps as a baseline and after seven different warm-up combinations (aerobic exercise, stretching, specific activity, aerobic exercise and stretching, aerobic exercise and specific activity, stretching and specific activity, and all three components) in random order on non-consecutive days. All jumps were simultaneously measured with RTT and ECM. Reliability was analyzed using the ICC (3,1) model for absolute agreement (AA) and consistency (CON) for all ten conditions (baselines and warm-up combinations). A repeated measures ANOVA determined validity by comparing differences between methods (RTT vs. ECM), conditions, and sex. RESULTS: The ten ICC values ranged from 0.451 - 0.516 for AA, and 0.852 - 0.909 for CON. VJ height was significantly lower (p<0.001) when measured using ECM (baselines: 28.8 ± 1.0cm, warm-ups: 29.0 ± 1.0cm) compared to RTT (baselines: 42.2 ± 1.4cm, warm-ups: 43.2 ± 1.2cm). There were method by sex interactions for baseline (p=0.047) and warm-up (p=0.021) conditions, but no significant method by condition interactions for baseline (p=0.246) or warm-up (p=0.053) conditions. There was also a significant three way interaction for baseline (p=0.021) but not warm-up conditions (p=0.842). CONCLUSION: These data suggest ECM is a reliable, but not valid, measurement tool compared to RTT. Although not significant (possibly due to a small sample size or short warm-up duration), ECM may experience different reliability levels after longer, or more intense exercise periods, due to alterations in jump mechanics which would affect the total flight time of the participant. This, however, requires further investigation.