the present work aimed at investigating relations between maternal child-rearing practices, externalizing behavior problems and social competence indicators of thirty-month-old children. the study involved 23 child-mother dyads. in the child's thirtieth month after birth, an observation of mother-child interaction was performed in order to evaluate maternal child-rearing practices, externalizing behavior problems and child social competence. the results support the literature about social development that relates child-rearing practices such as guidance, assertive control and positive parental involvement to social competence, and coercive and permissive practices to externalizing behavior problems. the work discusses the relevance of parental child-rearing practices for the comprehension of the social development, emphasizing the importance of child-rearing practices, such as autonomy authorization, intrusiveness and ambiguous control.