Objective: Research demonstrates mastery motivational climates are effective in increasing children’s physical activity (PA) and fundamental movement skills (FMS). In this study, we evaluated the effects of different types of mastery climate physical education (PE) lessons on PA and FMS. Methods: Participants in this 10-week randomized trial (N = 45, mean age = 9.0±0.5years, 48.9% boys) were randomly assigned to one of 3 mastery climate PE lessons: (1) FMS, (2) PA, or (3) FMS + PA. We conducted one-way ANCOVAs to determine differences between lessons on percentage of time spent in PA levels and changes in FMS scores. Results: There was a statistically significant effect of lesson type on moderate-to-vigorous PA (MVPA; F(2,40) = 7.730, p <.001), vigorous PA (VPA; F(2,40) = 4.372, p <.019), locomotion score (F2, 38 = 3.431, p =.043) and total FMS score (F2, 38 = 4.993, p =.027). Post hoc analyses revealed children receiving the FMS lesson had significantly higher MVPA levels compared to other lessons and higher VPA levels compared to the PA lesson (all ps <.05). Conclusions: Mastery climate FMS PE lessons are effective in increasing MVPA and VPA in elementary students. Continuing to incorporate FMS into the PE curriculum may be a valuable way to increase PA.