AbstractDevelopmental researchers have begun to explore parental cognitions in an effort to better understand adolescent parenthood. However, most research on adolescent mothers has failed to relate cognitions of the mother to the child's functioning. To extend the research on adolescent‐parent families, we examined the association between adolescent mothers' knowledge of child development, parental expectations, and child‐rearing beliefs to their infants' or toddlers' coping behavior. Trained observers rated children on the three subscales of the Early Coping Inventory–Sensorimotor, Reactive Behavior, and Self‐Initiated Behavior. The findings indicated that the adolescent mothers' self‐reports of their expectations for their own and their children's behaviors and emotions accounted for a significant proportion of the variance in objective ratings of the children's coping behavior in the sensorimotor and reactive behavior domains. Adolescent mothers who reported more positive, more realistic, and more mature expectations about parenting, children, and the parent‐child relationship had children who were rated to display more adaptive and effective sensorimotor and reactive behavior coping capacities. An interaction between the adolescent mothers' knowledge and beliefs significantly predicted self‐initiated child behaviors. Implications of the findings include the importance of exploring a “good match” in adolescent mother‐