Due to the significance of teachers’ beliefs and individual variables, a bulk of studies has focused on teacher characteristics over the past two decades. As an attempt to further clarify the interplay between teacher-related constructs in English as a Foreign Language (EFL) context, the present study set out to explore the structural model hypothesizing the predictive role of teachers’ self-efficacy and collective teacher efficacy in affecting the psychological well-being of teachers in Iranian EFL context. In so doing, a sample of 179 English teachers was given the three self-report scales measuring the variables under investigation. As for the statistical analysis, Structural Equation Modeling (SEM) was employed to test the fit of the hypothesized model. The results indicated that teacher self-efficacy accounted for 19.8% of the variance while collective teacher efficacy amounted to 11.3% of the variance in psychological well-being. In addition, it was revealed that although both predictors had a unique effect on psychological well-being, teacher self-efficacy was a stronger predictor of psychological well-being than collective teacher efficacy. The results and implications are finally elaborated.