The purpose of this study was to assess the influence of Bandura's (1997) theorized sources of self-efficacy on the academic and self-regulatory efficacy beliefs of 3rd-grade elementary school students (N = 395) in France, to examine whether classroom context might explain a significant portion of the variation in self-efficacy, and to assess whether these sources differ as a function of sex. Hierarchical linear modeling revealed that mastery experience, social persuasions, and mean classroom-level self-efficacy predicted mathematics self-efficacy. Mastery experience, social persuasions, physiological state, and mean classroom-level self-efficacy predicted French self-efficacy. All 4 sources predicted self-efficacy for self-regulated learning in both subjects, with the exception of vicarious experience in French. Classroom-level variables did not predict self-efficacy for self-regulated learning in either subject. Boys outperformed girls in mathematics and reported higher mathematics self-efficacy, self-regulatory efficacy, mastery experience, social persuasions, and lower physiological arousal. In French, girls outperformed boys but reported lower self-efficacy. Findings support and refine the theoretical tenets of Bandura's social cognitive theory. (Contains 4 tables.)