Research has identified high school and college students as the groups experiencing the greatest severity of loneliness. The manifestations of loneliness in adolescents and young adults were examined in a group of college (N=192) and high school (N=98) students. All subjects completed the Revised Loneliness Scale and a questionnaire about experiences with parents, peers, and school. College students completed the Loneliness Scale to reflect current feelings and the second questionnaire to reflect high school experiences. The high school students completed both instruments to reflect their current feelings and experiences. Analyses of the data identified 11 components of loneliness for each sample. Peer-related experiences dominated the components and the predictive models of loneliness. Six components (alienation, inferiority feelings, negative school experiences, social facility, social acceptance, and social integration) accounted for 72% of the variance in loneliness scores for high school students. Eight components accounted for 58% of the loneliness variance for the college students. Findings suggest that loneliness is accompanied by a variety of unpleasant feelings and negative perceptions of self and relationships with the social environment. (Author/NRB)