High-autonomy learning environments, such as mastery motivation physical play programs (MMPP), are effective in engaging toddlers in health-promoting physical play (Parish, Rudisill, and St. Onge, in press). This study found toddlers were more vigorously engaged for a longer portion of a MMPP than a nonplanned free play (NPFP) session (i.e., high autonomy, with limited teacher instruction and equipment). The current study sought to extend the work of Parish et al. (in press) by investigating heart rate patterns following a MMPP versus NPFP session in a sample (N = 21; 10 girls, 11 boys) of toddlers (M age = 2.59 years, SD = ±0.46) attending full-time daycare. Participants wore an Actiheart monitor to measure heart rate (HR), which was sampled every 15 s for 3 hr following 2 conditions, a MMPP and NPFP, which lasted 30 min each. Detailed heart rate profiles are provided and discussed. To confirm statistical significance, a repeated measures ANOVA (2 [Condition] x 6 [Time]) was conducted and revealed that heart rate remained higher for the 3 hr following a MMPP versus NPFP session (p < .01) for all participants. Although this study showed that heart rate remained higher following engagement in a MMPP session when compared with a NPFP session, further research is warranted to determine the cause of this finding.