Research on physical activity has revealed that physical activity may be beneficial for not only physical health, but also mental functioning (Center for Disease Control, 2014; Alexander, Allen, & Bindoff, 2013). For instance, physical activity has been shown to alleviate symptoms of stress responses, has shown promise in alcohol and substance abuse treatments, and has been shown to improve executive functioning in adult and adolescent populations (Taylor, Sallis, & Needle, 1985; Best, 2010). While little research on relations between physical activity and executive functioning in infancy and early childhood exist, the limited results have surprisingly revealed a negative relation between the two (Rothbart, 2001). To investigate these diverging patterns, we aimed to investigate a possible moderator of the physical activity-executive function association, namely, maternal encouragement of physical activity. Fifty-six children (26 boys) visited the lab at M = 18.3 months (SD = 0.43 months). The Early Childhood Behavior Questionnaire (ECBQ; Putnam et al., 2006) superdimension of effortful control was used as a surrogate measure of early executive function. To measure child activity level, we used the mother-reported activity level subdimension from the ECBQ, and also coded mother-child free play periods to quantify children’s predilection to use physical activity in the service of social or cognitive objectives, such as grasping a spoon and extending the arm outwards to feed a baby doll, which we termed sociocognitive activity. To measure sociocognitive activity we used a modified version of Tamis-LeMonda and Bornstein’s (1990) play competence scale wherein each instance of sociocognitive activity was noted and summed for a total score of sociocognitive activity level (See Table 1). Finally, to gauge maternal encouragement, a modified version of the Dyadic Parent Child Interaction Coding System (DPICS; Eyeberg, Nelson, Duke, & Boggs, 2005) was used to identify maternal commands, praise, questions, physical involvement, talking, touching, and scaffolding behaviors during mother-child free play sessions. Zero-order correlations revealed a significant negative relationship between mother-reported activity level and child executive function (r = -.42, p < 0.01), replicating previous findings. However, correlations between sociocognitive activity and executive function, while positive, was not significant. We conducted moderation analyses separately for each maternal encouragement variable, and found that a higher amount of maternal questioning during play corresponded to a positive association between sociocognitive activity and executive functioning (moderator = 1.00, p < 0.05). These findings partially support our hypotheses and suggest that the ways in which caregivers direct and train activity during play through questioning strategies may also direct and train cognitive functioning. However, further research is needed to support these claims. These results also point toward issues with the measurement of activity level, as our two measures of activity produced significantly different correlations with executive functioning (z = -3.4, p < 0.01). Future research in the area of motor development as it pertains to cognitive functioning should investigate and develop a standard measure of motor activity that is capable of capturing not only simple milestone achievement and intensity levels, but also the amount of sociocognitive engagement during physical activity.