--- - |2 Abstract Adolescents are often thought to be lonely because they distance themselves from their parents and are not fully integrated into the social world of their peers. Cacioppo's evolutionary model of loneliness, which has been applied primarily to adults, offers a complementary perspective. This model explains not only how feelings of loneliness emerge, but also how they are maintained. It also explains how loneliness can affect physiological functioning and health, and can spur changes in how people process information in the brain, as well as how genetic factors can affect loneliness. In this article, I use recent research to illustrate how the model sheds new light on loneliness in adolescence. I also suggest a comprehensive model of adolescent loneliness that combines key aspects of Cacioppo's evolutionary model with elements of other models. - Child Development Perspectives, EarlyView.