Bohannon, RW, Bubela, DJ, Wang, Y-C, Magasi, SS, and Gershon, RC. Six-minute walk test vs. three-minute step test for measuring functional endurance. J Strength Cond Res 29(11): 3240–3244, 2015—The purpose of this study was to compare 2 practical measures of functional endurance. Specifically, the six-minute walk test (SMWT) and three-minute step test (TMST) were compared to determine their appropriateness for use as field tests and inclusion in the NIH Toolbox for the assessment of neurological and behavioral function. Individuals between 14 and 85 years performed both the SMWT and TMST in random order. We documented completion rates, criterion performance, heart rate responses, and subjective exertion associated with the 2 tests. All 189 participants completed the SMWT, but only 73.0% completed the TMST. Those completing the TMST were more likely to be male, report better health, and have a younger age and lower body mass index. The SMWT distance was greater for those who did vs. those who did not complete the TMST. For those completing both tests, the average distance walked in 6 minutes was 595.9 m; the average cumulative heart beats during the minute after the TMST was 107.4. Distance walked and cumulative heart beats correlated weakly. Average heart rate and perceived exertion were significantly higher after the TMST than the SMWT. Posttest heart rate and perceived exertion for the 2 tests correlated significantly but not strongly. We conclude that the SMWT is more likely to be completed and is usually less stressful physiologically than the TMST and therefore may be a better option for field testing functional endurance and inclusion in the NIH Toolbox.