The purpose of this study was to examine the effect of parental psychological control, ambivalence over emotional expressiveness, and self-compassion on middle school students aggressiveness. It also measured the mediating effect of ambivalence over emotional expressiveness and self-compassion of the effects of parental psychological control on young adolescent s aggression. The participants were 580 middle school students attending four middle schools located in Seoul, Gyeonggi and, Jeollanam provinces. Self-report questionnaires were developed to measure the students aggressiveness, and they were administered along with parental psychological control scale (PCS-YSR), aggression scale (K-PCS), ambivalence over emotional expressiveness scale (AEQ-K) and self-compassion scale (SCS). In order to verify the mediating effects, descriptive statistical analysis, correlation analysis, and a structural equations verification model were used through SPSS and Mplus, and the bootstrapping method was used to verify the statistical significance of mediating effects. The results of this study could be summarized as follows. First, it was confirmed that there were a statistically significant correlations between parental psychological control and ambivalent emotional expressiveness as well as parental psychological control and ambivalence over emotional expressiveness. There were negative correlations between ambivalence over emotional expression and self-compassion as were as self-compassion and young adolescents aggression. Second, from the relationship between parental psychological control and young adolescents aggression, ambivalence over emotional expression and self-compassion were found to have sequential mediating effects. As the participants perceived that they possessed high psychological control, their ambivalence over emotional expression increased, and as their ambivalence over emotional expression increased, their self-compassion decreased, increasing aggressiveness. Finally, the limitations of this study and future research directions are suggested.