The purpose of this study was to measure and compare the Big Five personality traits of students attending the Public secondary schools of Mount-Lebanon and the Suburbs of Beirut, Lebanon and to shed light on the most important outcome of the Lebanese education system: student’s personality development. The study is conducted using a quantitative questionnaire about the Big Five personality traits, that are (Neuroticism, Extraversion, Openness, Agreeableness, and Conscientiousness), which is asked for a random sample of 500 students. The most noteworthy findings were: the ratio of the students’ personality traits of Conscientiousness and Extraversion are more dominant as compared to the remaining three Big Five personality traits; the Conscientiousness personality trait is the most dominant, whereas Neuroticism is the least dominant personality trait; and there was a significant difference between male and female students in two big personality traits (Conscientiousness and Agreeableness).