Applying the theory of planned behavior to explain aggressive behavior among Iranian adolescent girls: a structural equation modeling analysis

Aggressive behavior during adolescence is a major public health concern because of its adverse effects on mental health, academic achievement, and social functioning. The Theory of Planned Behavior (TPB) provides a well-established framework for understanding the cognitive and social determinants of behavior. This study examined the applicability of the TPB in explaining aggressive behavior among Iranian adolescent girls using a full structural equation modeling (SEM) approach. This cross-sectional study included 1059 adolescent girls aged 11–15 years attending public middle schools in Noorabad, southern Iran. Participants completed the Buss-Perry Aggression Questionnaire and a TPB-based questionnaire assessing attitude, subjective norm, perceived behavioral control, and behavioral intention to avoid engaging in aggressive behavior. Confirmatory factor analysis (CFA) was first performed to evaluate the measurement model, followed by SEM to examine the hypothesized structural associations among the TPB constructs and aggressive behavior. Construct reliability and convergent validity of the measurement model were evaluated using composite reliability (CR) and average variance extracted (AVE), and indirect associations were estimated using bootstrap resampling (5000 samples). Participants reported moderate levels of aggressive behavior and behavioral intention to avoid aggressive behavior. The measurement and structural models showed mixed but generally reasonable evidence of model fit, with the final structural model showing χ 2 /df = 2.85, CFI = 0.897, TLI = 0.892, IFI = 0.897, and RMSEA = 0.042. Attitude showed the strongest positive association with behavioral intention to avoid aggressive behavior (β = 0.60, p < 0.001), whereas perceived behavioral control demonstrated the strongest total association with aggressive behavior (β = -0.57, p < 0.001). Behavioral intention to avoid aggressive behavior was significantly associated with lower aggressive behavior (β = −0.34, p < 0.001), whereas subjective norm was not significantly associated with behavioral intention ( p = 0.177). The TPB constructs explained 74.9% of the variance in behavioral intention and 55.8% of the variance in aggressive behavior. The findings support the applicability of the TPB for examining aggressive behavior among Iranian adolescent girls. Perceived behavioral control showed the strongest association with aggressive behavior, whereas attitude demonstrated the strongest association with behavioral intention to refrain from aggressive behavior. Although subjective norms were significantly associated with behavioral intention at the bivariate level, their unique association was not statistically significant after accounting for attitude and perceived behavioral control. This finding should not be interpreted as evidence that social influence is unimportant, but rather as indicating limited unique variance explained by subjective norms within the full TPB model. The observed associations may provide hypotheses for future research examining whether school-based approaches targeting self-regulation, emotion regulation, and attitudes toward refraining from aggression are effective in reducing subsequent aggressive behavior. Given the cross-sectional design, these associations should not be interpreted as causal relationships.