Elementary-school children in Cuba and Canada participated in measures of loneliness, sociometric status, friendship, aggression, and social withdrawal. Withdrawal was associated with loneliness in the Cuban data from both cohorts, Grade 4 and Grade 6. In the Canadian data, withdrawal was only linked to loneliness in Grade 6. In contrast with North American data, aggression was a significant correlate of loneliness in the Cuban data from both cohorts. Social withdrawal was more strongly linked with loneliness in a Grade 6 cohort than among children in Grade 4. Especially in the Cuban Grade 6 data, there was considerable evidence that peer acceptance/rejection mediates the link between problematic social withdrawal and loneliness. These data are interpreted in light of the known functions of the peer group in Cuban society in regulating social behaviours that may be interpreted as not participating in the collective group or undermining its behavioural norms. (Contains 5 tables and 2 figures.)