The present study investigated the interplay between language anxiety, locus of control, and language proficiency of EFL students in online classes. The participants of the study were 67 upper-intermediate students between 18 to 30 years old and were selected randomly from a few language institutes in Shiraz. Two questionnaires and a proficiency test were used: Chametzky’s Online World Language Anxiety Scale, Rotter’s Locus of control questionnaire, and The Examination for the Certificate of Proficiency in English. Pearson-product-moment correlation, multiple regression analysis, and independent-samples t-test were run to answer the research questions. The results of the study revealed a strong negative correlation between locus of control and language proficiency, meaning that those who had higher scores on the proficiency test were internal. In addition, a strong negative correlation was found between language anxiety and language proficiency, indicating that anxiety has adverse effects on language proficiency. Thirdly, both locus of control and language anxiety could predict language proficiency, but the former was a better predictor. This means that the effect of locus of control is much higher than anxiety on the language proficiency of Iranian EFL learners in online classes. This research can help students and teachers to recognize individual differences better. پرونده مقاله