This study was conducted in order to develop and validate a school adjustment scale for school-aged children. Methods: Data were collected from a sample of 4th, 5th and 6th grade students in five elementary schools located in Seoul. A total of 1,055 children were administered a school adjustment scale with 97 items. After a series of analyses, 30 items were retained. The validity of these items was verified by 1,082 children. Data were analyzed by means of exploratory factor analysis, confirmatory factor analysis, and correlation analysis. Results: The results of factor analysis identified four factors Academic Attitude/Rule Observance, Relationships with Peers, Relationships with Teachers, and School Satisfaction. Cronbach's α ranged from .91 to .93, indicating a high level of internal consistency. Concurrent validity was established using correlations of children's school adjustment with mothers' parenting behaviors and children's social competence, self-esteem, and ego resilience. Cross-validation was also verified for the four subscales. Conclusion: Considering its reliability and validity, the scale evaluated in the current study would serve as a useful tool for assessing school adjustment in late childhood.