The purpose of this study was to determine the effectiveness of a planned mastery motivational physical play session on physical activity (i.e., heart rate [HR] and physical play intensity [PAHR greater than 50]) in toddlers (N = 21), as compared to a nonplanned free play session. Participants wore a monitor to measure HR over two, 30 min play conditions. A multivariate analysis of variance was conducted to evaluate the effect of the play conditions. A significant difference between conditions and physiological measures revealed that the mastery motivational physical play session resulted in higher HR and PAHR greater than 50 when compared to free play. These findings suggest the mastery motivational session resulted in more vigorous physical play in toddlers than free play. (Contains 1 table.)