The purpose of this study is to reveal the extent to which the sources of 6th- 8th grade students' self-efficacy beliefs predict their self-efficacy beliefs for learning and performance. The study is correlational and was conducted on a total of 1049 students during the fall term of the educational year 2010-2011. The data of the study were collected through "The Scale of Determining the Sources of Self-Efficacy" and "The Scale of Self-Efficacy for Learning and Performance". The data were analyzed on the basis of the arithmetic mean, standard deviation, Pearson product-moment correlation coefficient and stepwise regression. The students stated that their self-efficacy beliefs were developed mostly by verbal persuasion and performance accomplishments. They also noted that psychological states and vicarious experiences develop their self-efficacy beliefs at a lower level. It is the factor "performance accomplishments" that is correlated with the students' self-efficacy beliefs and predicts them in the strongest way. Apart from performance accomplishments, the factors "vicarious experiences" and "verbal persuasion" predict the students' self-efficacy beliefs for learning and performance.