This article investigated the relationship between EFL teachers' self-regulation and teaching effectiveness. In so doing, 76 EFL teachers were selected according to a convenience sampling from different English language institutes in Mashhad, a city in north-eastern Iran. The findings of the study indicated that there is a significant relationship between EFL teachers' self-regulation and their teaching effectiveness. Subsequent data analyses indicated that among the components of self-regulation, intrinsic interest, mastery-goal orientation, and emotional control have the highest correlations with teaching effectiveness. Based on the findings of the present study teacher educators, administrators, and policy makers are recommended to incorporate self-regulated learning strategies to teacher training programs. The findings of the present study may also highlight the contributing roles of intrinsic and emotional factors in teaching effectiveness.