The purposes of this study were: (1) to investigate the relationships among SES, child-rearing attitudes, mythof nonassertion, school environments, assertiveness and adjustment of junior high students; (2) to examine and modify the casual path model. In this study, 941 subjects were sampled from the population of junior high students in Taipei City. The dependent variables were the scores of parental child-rearing attitudes, myths of nonassertion, assertiveness (included self-respectiveness and self-expression), self-confidence, social anxiety, and interpersonal relationships. And the independent variables were sex, nature of school (i. e. school was consisted of the only sex students or male and female students), nature of class (i.e. the class members were the only sex students or included male and female students), experience of class cadre, experience of noncurricular activity in the school, and ability grouping. The data were analyzed by Pearson-product correlation, univariate three way analysis of variance, multiple-stepwise regression, and path analysis statistics methods. The results revealed that, (1) socioeconomic status, child-rearing attitudes, experience of class cadre, experience of noncurricular activity in the school, the nature of school, ability grouping, and the scores of myths of nonassertion (excepted the myth of good friend), self-confidence, social anxiety, and interpersonal relationships were significantly correlated with assertiveness of junior high students; (2) there were interactions among ability grouping, sex, and the nature of school in the scores of self-respectiveness and total score of assertiveness; similary, there were interactions among ability grouping, sex, and the nature of class in the score of self-expression; (3) the path model got some statistical support.