An investigation into the relationship among Iranian EFL learners’ Emotional Intelligence, Willingness to Communicate, Autonomy, and L2 achievement Abstract: The purpose of the present study was to investigate the relationship between emotional intelligence, willingness to communicate, autonomy, and L2 achievement of Iranian EFL learners. To this end, 150 EFL learners majoring in English at Bu-Ali Sina University in Hamedan, and Islamic Azad Univesity of Hamedan were selected as the subjects of the study. The subjects took Bar-On EQ-I questionnaire validated by Rahimi (2014), willingness to communicate questionnaire developed by MacIntyre et al. (2001), and completed a learner autonomy questionnaire based on the questionnaire by Conttia (2007), revalidated by Soodmand Afshar and Bastami (2012) for Iranian context, and also subjects’ GPAs were collected from the Registrar’s office of both universities. Using Cronbach’s Alpha and factor analyses, the willingness to communicate questionnaire was found to have acceptable reliability and validity rates. The results of five correlations indicated that there was a statistically significant: 1) positive correlation between emotional intelligence and willingness to communicate, 2) positive correlation between emotional intelligence and autonomy, 3) positive correlation between emotional intelligence and L2 achievement, 4) positive correlation between willingness to communicate and L2 achievement, 5) positive correlation between autonomy and L2 achievement. Furthermore, the results of the multiple regression analyses indicated that, willingness to communicate was the strongest predictor of L2 achievement of Iranian EFL learners followed by emotional intelligence. The findings of the study imply that learners, who enjoy emotional intelligence, willingness to communicate, and autonomy are higher achievers. The results as well as the implications of the study are discussed in more detail in the thesis.