Two studies were conducted to assess children's loneliness, aggression, withdrawal, and social competence associated with peer rejection across a 1-year period. At the first assessment, sixty 4-year-olds (Study I) and fifty -nine 5-year olds (Study II) were administered measures of positive and negative sociometric nominations and peer behavioral assessments of aggression, withdrawal, and social competence. At the second assessment one year later, all measures were repeated with the addition of a self-report measure of loneliness. Social status groups of popular (P), rejected (R), average (A), neglected (N), and controversial (C) children were identified each year. Children of the R 2 group who were rejected by peers at both the first and the second assessment were more likely to be aggressive and socially incompetent, and reported higher levels of loneliness than children of other groups in both of two studies. These findings suggested the possibility that chronicity of peer rejection increased loneliness and aggression, and retarded the development of social competence in young children.