The purpose of this study was to determine the test-retest reliability and construct validity of tools to assess how balance confidence (BC) and state anxiety (SA) change with progressively increasing walking speeds. Sixteen young adults and 15 older adults attended two sessions. Individuals began walking on a treadmill at 0.4 m/s Participants chose to continue increasing the treadmill speed (up to 2.0 m/s) or to discontinue the protocol while rating their BC and SA after completing each speed. BC at participants’ fastest speed attempted demonstrated high and moderate test-retest reliability among young (intraclass correlation coefficient [ICC] = .908) and older adults (ICC = .704). SA for young adults and older adults was good (ICC = .833) and fair (ICC = .490), respectively. Our measures also correlated with measures of dynamic stability while walking for young (r = -.67, p = .008) and older adults (r = .54, p = .046). Our dynamic measures of BC and SA are valid and reliable in young and older adults.