The purpose of the present study was to examine relations between self-perceptions of competence and social, behavioural, and school adjustment in Brazilian, Canadian, Chinese, and Italian children. Self-perception data were collected through children's self-reports. Information about social behaviours, peer acceptance, and school achievement was obtained from peer assessments and teacher ratings. Multi-group analyses revealed similar patterns of relations between self-perceptions in scholastic and general self-worth domains and social and school performance in the four samples. However, the relations between self-perceptions of social competence and shyness and academic achievement were different across these samples. Self-perceptions of social competence was negatively associated with shyness in Brazilian, Canadian, and Italian children, but not in the Chinese children, and positively associated with academic achievement in Canadian and Chinese children, but not in Brazilian and Italian children. Similarities and differences in the patterns of relations between self-perceptions and social and school adjustment across cultures indicate that the self system may be a culture-general as well as culture-specific phenomenon. (Contains 4 tables.)