The present study aimed to examine the effectiveness of assertiveness training on self-awareness and aggression among elementary school students in the city of Someh Sara.The research employed a quasi-experimental design with a pretest–posttest and a control group. The statistical population included all male students in the fifth and sixth grades enrolled in public schools in Someh Sara during the 2024–2025 academic year. The sample consisted of 28 students (14 in the experimental group and 14 in the control group), selected purposefully, and assessed using the Fenigstein, Scheier, and Buss (1975) Self-Awareness Questionnaire and the Shaheen (2006) Elementary School Aggression Inventory in both pretest and posttest phases. The experimental group received eight sessions of assertiveness training, while the control group remained on the waiting list. Data analysis was performed using descriptive statistics (mean, standard deviation, frequency, and percentage) and inferential statistics (ANCOVA) via SPSS version 26. Findings indicated that assertiveness training significantly improved self-awareness and reduced aggression among elementary students. It can be concluded that enhancing assertiveness skills can substantially increase self-awareness and decrease aggressive behaviors in elementary school students.