This study aims to examine the mediating role of basic psychological need satisfaction in the relation between adolescents' emotional insecurity and overt and relational aggression behaviors, through the lens of Emotional Security Theory and Self-Determination Theory. The participants were 234 adolescents attending middle or high school, mostly from middle socioeconomic status. The participants' ages ranged from 11 to 18 years, with a mean age of 15.60 (49% male). The Emotional Security Scale, the Basic Psychological Needs Satisfaction Scale, and the Children's Social Behavior Scale were used to collect data. The main mediation analysis was conducted using path analysis from structural equation models. As a result of the path analysis, it was found that adolescents' increased emotional insecurity decreased their basic psychological need satisfaction, which in turn, was associated with more overt and relational aggression behaviors; and basic psychological need satisfaction mediated the relationship between adolescents' emotional insecurity and overt and relational aggression behaviors. Supplementary analyses showed that only relatedness need satisfaction mediated the relationships between adolescents' emotional insecurity and both overt and relational aggression behaviors. The research findings are discussed in the context of the two theories, by taking culture into account.