English language skills are considered of great value in the labor market and in research. As such, learning English as a Foreign Language (EFL) is of great importance, especially for international students and employees working internationally. The goal of the present study was to explore student self-efficacy in language learning (LSE) and compare it to general self-efficacy (GSE) and effort (EF) as predictors of student English reading comprehension performance. The participants in this study were EFL students enrolled in academic English courses for one three-month academic semester. Using a longitudinal design, the sample of 265 participants completed three questionnaires: GSE, LSE, and EF scales at Time 1, the beginning of the semester. At Time 2, upon course completion, a reading comprehension test was given to all participants. Results indicate that LSE, and not GSE, is positively correlated with reading comprehension performance. Furthermore, the data showed that LSE is positively correlated with effort and that effort is positively correlated with reading comprehension performance. Further analysis revealed that effort mediates the relationship between LSE and reading comprehension performance. Our study will contribute to developing more effective teaching methods and provides EFL teachers with the necessary tools to predict and enhance student achievements. Implications and limitations for future research are discussed.