The present study examines the associations between peer acceptance and friendship with loneliness, self-esteem and school engagement in a sample of 180 primary school pupils (M age = 10.94 years old, SD = 0.82, age range: 9-12 years). Peer acceptance was evaluated through a sociometric procedure, the number of children's mutual friendships through peer nominations and friendship quality, while self-esteem and loneliness were assessed through self-report questionnaires. Peer-rated acceptance/popularity and provision of help by friends in school were both found to contribute significantly to pupils' self-esteem and to their tendency not to avoid school. Security in friendship emerged as a moderately significant factor in predicting feelings of loneliness or school liking, while companionship among friends was found to protect moderately from loneliness in school. The present research findings support previous evidence attesting to the link between friendship-related factors and children's psychosocial adjustment in the school environment.