This research intended to examine the influence of English as a Foreign Language (EFL) teachers' self-efficacy, job satisfaction, and reflective thinking on their professional development. Two-hundred and twelve Iranian EFL teachers from different universities, language institutes, and schools participated in the research. They were requested to answer Teachers' Sense of Efficacy Scale, The Minnesota Satisfaction Questionnaire, Reflective Thinking Scale, and Professional Development Questionnaire as the main data collection instruments. The questionnaires were submitted in three different ways: email, social networks and in person. Structural Equation Modeling on SPSS AMOS version 24 was employed to examine the hypothesized model of relationships. This model was confirmed following the application of the modification indices suggested by the software (Normal chi-square=3.6; RMSEA=0.03; RMR=0.02; GFI=0.93; AGFI=0.90; NFI=0.92; CFI=0.93; IFI=0.93). The findings showed significant internal correlations between all the latent variables along with their sub-scales. Furthermore, multiple regression analysis showed that self-efficacy and job satisfaction positively predicted professional development, with self-efficacy exerting more predictive power compared to job satisfaction. It was further found that not only did reflective thinking not predict professional development, but, conversely, it was partly predicted by professional development. Pedagogical implications of the study have been discussed.