The purpose of the present study is to examine Case's neo-Piagetian Theory in Korean Culture. The hypotheses examined in this study are as follows: H. 1) There would be a similar orderly developmental sequence across the tasks; H. 2) There would be the developmental level to be reached according to the age; H. 3) There would be the parallel of developmental rate across the tasks according to the age; and H. 4) There would be the asychrony in intraindividual development across the tasks. Three experiments were conducted : Experiment 1 was designed to test H.1, experiment 2 to test H.2, and experiment 3 to test H.3 and H.4. The sample for each of the three experiments consisted of 80 children between 3 and 11 years of age, 20 at each of following four grade levels: junior kindergarten, grade 1, 3, and 5. The mean chronological age for each grade was : junior kindergarten 3.9(SD=0.31) ; grade 1, 6.7 years(SD=0.22) ; grade 3, 8.6 years(SD=0.30) ; grade 5, 106 years(SD=0.25) The Noelting's Juice Mixing Task, the Wagner's Figure Analogy Test, and the Kim and Lee's Area Quantity Task were used to test H.I. The Case's Balance Beam Task and the Chandler's Intelligence Attribution Task were used to test H.2. And the Noelting's Juice Mixing Task, the Marini's Birthday Party Task, and the Kim and Lee's Reward Sharing Task were used to test H.3 and H.4. Some of the tasks were to assess children's scientific reasoning while others were to assess children's social cognition. Each task was administered by the present researcher on an individual basis The testing session took place in a private room at the children's school. Each task lasted from 15 to 20 minutes, depending on the child. An entire session thus lasted between 45 to 60 minutes. The results of the present study were as follows: ① It was found the percentage of children succeding on the Juice-mixing task decreased as the level of task complexity increases. A similar sequence of performance was observed on the Figure Analogy Task and the Area Quantity Task. The results also showed that there were no instances where the child who failed level 1 would pass level 2, 3, or level 4. Then, the hypothesis of a similar sequence of performance across the three tasks was confirmed. ② The results revealed that Level 1. 2. 3, and 4 of the two tasks were passed by the majority of the children at grade JK. 1. 3. 5, respectively. Thus, the second hypothesis of age appropriate performance was confirmed. ③ It was found that the rate of performance on each of the three tasks was very similar. An ANOVA showed no task effect [F(2, 216)= .833. p＞.05] or interaction [F(6, 216)=1.752, p＞.05] and a strong age effect [F(3. 216)=179.268. p＜.01]. Thus, the third hypothesis of parallels in rate of development across the tasks was confirmed. ① The results showed that children performing at one level different between the Juice-mixing Task and the Birthday Party Task, between the Juicemixing Task and the Reward Sharing Task, and between the Birthday Party Task and the Reward Sharing Task were 43%, 44%, and 9%, respectively. Thus, the fourth hypothesis of domain-specific performane at the individual level was confirmed. These results suggest that, beyond culture and race, development can be characterized as having “horizontal structure”, that is, as progressing through a similar sequence, and at a similar rate across domains. Therefore, Case's neo-Piagetian Theory seems be a powerful theory for explaining children's intellectual development across culture and race.