The purpose of this study was to explore the predictors of negative attitudes towards learning English from L2 learners’ points of view. A mixed methods research approach was adopted with a sequential exploratory design, followed by an endorsement phase. Eighteen high school students in Fars province (Iran) were interviewed on the sources of negative attitudes towards learning English. Based on the interviews, a questionnaire was developed and pilot-tested. Results of exploratory factor analysis (EFA) showed 6 latent variables: materials, difficulty of learning English, affective factors, teaching methodology, school policy, and learning environment. Questionnaire was administered to 980 high school students. Through a confirmatory factor analysis (CFA) and simple linear regression, we found that the variable materials was the best predictor of negative attitudes. Then, came the variable affective factors that predicted negative attitudes better than the variables teaching methodology and learning environment, and the least predicting variable was difficulty of learning English.