Empirical research has provided evidence supporting the validation and prediction of 4 major sources of self-efficacy: enactive performance accomplishments, vicarious experiences, verbal persuasion, and emotional states. Other research studies have also attested to the importance and potency of self-efficacy in academic learning and achievement. Despite this emphasis, very few, if any, research has explored the impact of the 4 sources of information on self-efficacy from a developmental perspective. The author used latent growth modeling to explore the impact of the 4 sources of information on self-efficacy over 4 occasions. This methodological approach, similar to recent studies (Caprara et al., 2008), is significant, as it allowed the author to trace the developmental trajectories of elementary school children's self-efficacy beliefs in English and mathematics over time. Three hundred and thirty-nine 3rd- and 4th-grade students (147 girls, 192 boys) took part in this study. Two Likert-type inventories were administered and the data collected were analyzed with the statistical software SPSS AMOS 18. Causal modeling analyses indicated that children's self-efficacy for English and mathematics learning increased over time. Furthermore, of the 4 informational sources, enactive performance accomplishments associated closely with the growth of change of English and mathematics self-efficacy beliefs. Children's emotional states also associated negatively with the growth of change of mathematics self-efficacy. Enactive performance accomplishments and verbal persuasion associated positively with the initial levels of English and mathematics self-efficacy. Finally, the results provide methodological support for the psychometric properties of the inventories used. (Contains 1 note, 2 tables and 3 figures.)