It particularly aimed at investigating the relationship between self-esteem and gender, grade level, and academic achievement among a sample of Lebanese Secondary school students: grades 10, 11 and 12. Six schools were randomly sampled and one section of each grade was randomly chosen. Participants were 479 students of whom 235 were males and 244 were females. The students responded to Culture-Free Self-Esteem inventory questionnaire (CFSEI-3). SPSS was used for analyzing data, using ANOVA design. The results revealed no significant gender difference in the Global, General, Academic, Parental and Social self-esteem subscales. Whereas the results showed a significant difference between males and females in the Personal self-esteem subscales. The results also revealed a significant difference between grade levels in the Global, General, Academic, and Social self-esteem subscale while no significant difference was recorded in the Personal and Parental self-esteem subscales among those grade levels. No significant interaction between gender and grade level in the Global, General, Academic, and Social self-esteem subscales. However, a significant interaction was noticed in the Personal self-esteem subscale. There was a significantly low correlation between self-esteem and academic achievement in the Global, General, Academic, and Parental self-esteem subscales, but no significant correlation was revealed between Social and Personal self-esteem subscales and academic achievement in the whole sample and in grades 10 and 11. In the case of grade 12 a significant correlation was recorded between the Global, General, Academic self-esteem and academic achievement. No significant difference was recorded between the Parental, Social and Personal self-esteem subscales and academic achievement of grade 12 students. Finally, z scores revealed no significant correlation differences across grade levels. Some findings with regards to the relationship between gender, grade level and interaction were noted concerning the six individual schools represented in the sample. Results were compared and discussed.