The present research was a 2-year longitudinal study of the self-concept development of primary schoolchildren in Hong Kong. Samples of primary grades 1, 3 and 5 students were followed through to primary grades 2, 4 and 6, respectively. Data on students' self-concept in four domains (academic, appearance, social, general) were collected at half-year intervals. The depression level of students and evaluations by teachers and parents on students' self-concept were obtained as well. Younger children were found to be higher in self-concept than older children, and a clear linear and downward trend was observed: the drop in self-concept was most drastic from primary 1 to 3 and leveled off thereafter. Girls were found to be higher than boys in all domains of self-concept, but their drop in self-concept was much greater. Self-concept was highly predictive of depression; primary 3 children were found to be higher in depression than primary 5 children. Evaluations by teachers and parents related closely to the children's self-evaluations on self-concept. In all, the present research was able to show a clear picture of the self-concept development of Chinese primary schoolchildren in Hong Kong. Implications of the findings are discussed.