This study examined how parenting style at 9 months predicts growth in infant social engagement (i.e., social smiling) between 9 and 18 months during a free-play interaction in infants at high (HR-infants) and low (LR-infants) familial risk for autism spectrum disorder (ASD). Results indicated that across all infants, higher levels of maternal responsiveness were concurrently associated with higher levels of social smiling, while higher levels of maternal directiveness predicted slower growth in social smiling. When accounting for maternal directiveness, which was higher in mothers of HR-infants, HR-infants exhibited greater growth in social smiling than LR-infants. Overall, each parenting style appears to make a unique contribution to the development of social engagement in infants at high- and low-risk for ASD.