This study examined the development of self‐regulation during early childhood and the reciprocal relations between self‐regulation and maternal sensitivity. Data (N = 1,364) were drawn from the NICHD Study of Early Child Care and Youth Development (NICHD SECCYD). Children's situational and committed compliance were assessed in the laboratory at 24 and 36 months, delay of gratification at 54 months, self‐control at 54 months and kindergarten age, and maternal sensitivity was observed at 24, 36, and 54 months. Self‐regulation was characterized to progress from situational compliance to committed compliance and then to fully self‐motivated regulation. Findings also suggest that the development of self‐regulation reflects an ongoing transactional process in which child self‐regulation and maternal sensitivity mutually influence each other.