This study aimed at testing a model in which teacher emotions predict teacher efficacy via emotion regulation. A total of 336 public middle school science teachers participated in the study. Data were collected through the Positive and Negative Affect Schedule, the Emotional Control Scale, and the Teachers' Sense of Efficacy Scale. Structural equation modelling was employed for data analysis. Results of the study revealed a significant relationship between teacher emotions and teacher efficacy through the partially mediating role of emotion regulation. That is, positive emotions had an influence on teacher efficacy (teacher efficacy for instructional strategies, classroom management, and student engagement) -- both directly and indirectly through their use of emotion regulation strategies. In addition, findings indicated that positive emotions were positively associated with emotion regulation, whereas negative emotions were negatively related. Positive emotions also predicted teacher efficacy while negative emotions did not. Lastly, emotion regulation had an influence on teacher efficacy.