The purpose of this study was to evaluate the psychometric properties of a Perceived Benefits Scale, a Perceived Barriers Scale, and a Physical Activity Enjoyment Scale with data from a group randomized controlled trial (RCT) and a test-retest study with 1-week interval. In the group RCT at baseline and Week 17, 1,012 fifth- to eighth-grade girls completed an iPad-delivered survey and wore 7-day accelerometers measuring moderate-to-vigorous physical activity (MVPA). In the test-retest study, 91 fifth- to seventh-grade girls completed the iPad-delivered survey at Times 1 and 2. Benefits, barriers, and enjoyment scales had Cronbach's as of 0.75, 0.86, and 0.78 and test-retest reliability of 0.83, 0.88, and 0.79, respectively. Benefits Scale had a two-factor structure (physical and psychosocial benefits), while the remaining two had a one-factor structure indicating construct validity. Barriers (r = -0.16) and enjoyment (r = 0.17) were correlated with MVPA indicating concurrent validity. Baseline MVPA and psychosocial benefits positively, while physical benefits negatively, predicted MVPA at Week 17 indicating predictive validity. The measures demonstrated satisfactory psychometric properties.