A bulk of research has been conducted to investigate the relationship of the personality traits of students with their academic achievement in international context. This area, however, has yet been rarely explored in the context of Pakistan. This cross-sectional survey study, therefore, investigated the degree to which selected primary source traits of the personality of students can serve as a predictor of their academic achievement at secondary school level in the context of Pakistan. Three hundred fifty seven (357) secondary school students (182 boys and 175 girls) attending class 10th participated in this study. A 43-item Likert 5-point trait scale, following the example of the items included in the ''Big Five Questionnaire -- Children version (BFQ-C)'' by Barbaranelli et al., (2003), was developed for measuring the eight selected primary source traits, namely: independence, intelligence, sociable, easy going, generous, friendly, emotionally stable, and dominance. Academic achievement of the representative sample of the students was measured on the basis of their annual examination results of class 9th. Collected data were analyzed and interpreted by applying descriptive and the inferential statistics as well as factor analysis. Values of regression analysis revealed that, among the eight primary source traits, "Independence", "Intelligence" "Emotionally stable" and "Friendly" were the only factors that predicted students' academic achievement to some extent while the role of other four traits found to be minimal or negative in predicting academic achievement.