The purpose of the study was to construct the Work Adjustment Index (WAI) for junior high school teachers and to examine its validity. The index was constructed based on a lifestyle analysis. A total of 472 junior high school teachers completed the LOHAS lifestyle questionnaire. The survey data was analyzed using a classification and regression tree (CART) and logistic regression. The results of the study indicated that: (a) there were seven classification trees and one was optimal for constructing the WAIbased on two categories, one is “stay in the same position ”, and the other is “go away”(b) the WAI was composed of 6 items with different weight on their alternatives, and (c) validity was conducted through criterion validity and group comparison method. Significant differences on WAI  were found for gender, job position, and teaching years, and there was significant positive correlation between stress against and work adjustment. The CART and logistic regression are good methods for constructing the WAI and this measure is useful in assessing teacher work adjustment.