Identity achievement has been described as a critical developmental task of adolescence, but has seldom been discussed in the context of adolescent parenthood. Little is known about how teen mothers negotiate identity development, nor about the role that the latter plays in influencing the teen parenting context, for example parenting quality and experienced stress. In the present study, data were collected from 42 adolescent mothers (younger than 20 years at childbirth), and 53 adult mothers (older than 24 years at childbirth). Identity achievement and perceived stress were assessed through self-report inventory, and parenting quality was assessed with behavioural observation of dyadic sensitivity. Results suggest that teen mothers follow a unique developmental sequence. Identity commitment, a component of identity achievement, emerged as a protective mechanism for young mothers. Specifically, identity commitment was found to mediate the relationship between maternal age and dyadic sensitivity, and moderate the relationship between perceived stress and dyadic sensitivity. Overall, findings from this study suggest that identity development may help calibrate stress and support adaptation to parenting among teen mothers, and could be another noteworthy factor in the development of healthy attachment relationships between adolescent caregivers and their infants.