The purpose of this study was to investigate the increase in IQ for Taiwanese children over the past 10 years. WISC-III and WISC-IV scores were collected following a counter-balanced design, based on a sample of 121 children aged 6 to 16 years old. The comparison between the WISC-IV and the WISC-III showed a mean difference of 1.23 FSIQ points. However, only five subtests were shared between WISC-III and WISC-IV full IQs. To partial out possible variations due to content differences, we estimated the increase in IQ based on the 10 core subtests of the WISC-III. Increased IQs over the intervening 10.5 years were 2.5 points, yielding an estimated growth of 0.24 IQ points per year. While America and other developing countries were still reporting an increased rate of 0.30 IQ points per year, increased IQ for Taiwanese children seemed slower than what the Flynn effect would have indicated. Current findings have matched recent reports from Scandinavian nations that the increase in IQ is slowing. Finally, Taiwanese children showed, comparatively, the largest gain on visual symbol search and nonverbal fluid reasoning abilities. However, Taiwanese children aged 10 to 16 showed no improvement in social and ethical reasoning, and those aged 6-12 showed a salient decline in the breadth of basic information. Possible hypotheses were discussed.