The associations between self-perception and attachment orientations and three aspects of children's competence within friendships were examined: "Managing conflict", "seeking support", and "giving support". Questionnaires were completed by 260 4th- and 5th-grade students. Homeroom teachers reported on the children's social adjustment. Secure attachment orientation and positive self-perception were positively associated with prosocial friendship competencies, and negatively associated with disengaging strategies. By contrast, ambivalent attachment was related to accommodation strategy and to disengaging strategies in the context of seeking and giving support. Girls and boys showed different levels of competencies within friendships; the results also demonstrate that engaging and disengaging strategies might function differently for boys and girls, and reveal the moderating role of attachment. The role of culture in children's competencies and the implications for intervention for children with friendship difficulties are discussed.