This is the third-year report of a convergence study on the intellectual development of Chinese children and adolescents in their school years. The subjects, 2115 students for the cross-sectional approach and 654 students for the longitudinal approach, were drawn by stratified sampling from two elementary schools and two junior high schools in Taipei area. Proressive Matrices and The Chinese Revision of WISC-R were adminitered to the subjects. The obtained data were statistically treated by analysis of variance, trend analysis, t test, and Pearson product-moment correlation. The main findings of the study were as follows: 1. The test scores for global intelligence and primary mental abilities of Chinese school children tended to increase with increasing age. 2. The growth of intelligence of Chinese school children was most rapid in primary grades and tended to increase thereafter at a progressively decreasing rate. 3. There was significant correlation between intelligence and academic achievement of Chinese school children. In addition, verbal intelligence correlateed much more highly than nonverbal intelligence with academic achievement in various subject-matter fields.