Study aim: General Objective To determine the effectiveness of short-term solution-focused therapy on aggressive behaviors, interpersonal sensitivity, problem-solving ability, and social skills among female upper secondary school students. Design: A quasi-experimental pretest-posttest control group study is conducted with 30 female students, randomly assigned to intervention and control groups (15 each). The intervention group receives eight 60-minute sessions of Brief Solution-Focused Therapy. Settings and conduct: The study involves 30 female students from an upper secondary school in District 4 of Isfahan, selected by multistage cluster sampling and randomly assigned to intervention and control groups. The intervention group receives eight weekly 60-minute SFBT sessions. Participants/Inclusion and exclusion criteria: Inclusion criteria: Female students in the 10th, 11th, or 12th grade of upper secondary school; provision of informed consent by the student and parent(s); and ability to participate in group sessions and complete research instruments. Exclusion criteria: Presence of an acute psychiatric disorder or physical/sensory conditions affecting the ability to participate in the study; concurrent participation in counseling programs or educational workshops related to the study variables; and unwillingness to continue participation in the study. Intervention groups: Intervention group: Participants in this group receive Brief Solution-Focused Therapy in a group setting. The intervention consists of eight weekly 60-minute sessions conducted at the school. Control group: Participants in this group do not receive Brief Solution-Focused Therapy during the intervention period and remain under standard school educational conditions. Main outcome variables: Aggression; interpersonal sensitivity; problem-solving ability; social skills.