The purpose of this study is to investigate the relationships among students' academic self-efficacy, academic optimism, family income and academic achievement. Two studies were conducted in order to reveal the relationship between students' optimism, self-efficacy and their achievement. Firstly, Academic Self-Efficacy and Student Academic Optimism scales were adapted into Turkish. Then, the relationships among the variables were tested. The sample of the study, which included high school students randomly selected from 8 different schools, consisted 274 participants for the adaptation study and 777 participants for the main study. The results of the SEM analysis did not validate the model yet revealed that academic self-efficacy is the strongest predictor of achievement and that both family income and academic self-efficacy directly affect achievement.