<![CDATA[Nice girl syndrome poses a challenge to female students’ social lives, and assertiveness plays a key role in minimizing its effects. This study aims to examine the influence of the Big Five personality traits and self-esteem on the assertiveness of students with nice girl syndrome, using an associative, cross-sectional approach. A total of 148 female 10th-grade students at SMA Negeri 10 Padang who exhibited an extreme level of nice girl syndrome were selected through purposive sampling. Research instruments included the Engel Nice Girl Syndrome instrument, an assertiveness scale developed by the research team, the Rosenberg Self-Esteem Scale, and the adapted Big Five Inventory. All instruments have demonstrated acceptable psychometric characteristics, with factor loadings ranging from 0.277 to 0.809 and Cronbach’s alpha coefficients ranging from 0.70 to 0.875. Findings showed that two dimensions of the Big Five personality traits have a significant effect on the assertiveness of students with nice girl syndrome, namely conscientiousness and openness, with p-values of 0.033 and 0.023, respectively. Self-esteem showed the strongest and most significant effect on the assertiveness of these students, with a p-value of 0.002. Simultaneous testing of the Big Five personality traits and self-esteem on the assertiveness of nice girl syndrome students also revealed a significant influence with a p-value of 0.000 <0.05. The coefficient of determination indicated that these variables jointly predicted 26.8% of the variance in assertiveness among students with nice girl syndrome. These findings can serve as a basis for developing school-based counselling interventions that address personality characteristics and self-esteem as key factors in enhancing assertiveness among students with nice girl syndrome.]]>
