This study examined how shyness-sensitivity and unsociability were associated with social, school, and psychological adjustment in Chinese children and adolescents. Participants included 564 children (272 boys, M[subscript age] = 9 years) and 462 adolescents (246 boys, M[subscript age] = 13 years) in a suburban region in China. Data were obtained from peer assessments, sociometric nominations, teacher-ratings, self-reports, and school records. The results showed that relations of shyness and unsociability with adjustment differed in middle childhood and early adolescence. Shyness tended to be associated with social and psychological problems more evidently in adolescence than in childhood. In contrast, unsociability was associated with problems more evidently across domains in childhood than in adolescence. The results indicate that the implications of the two main forms of social withdrawal may vary across developmental periods.