Purpose: Teacher effectiveness has been a matter of concern not only for the parents and students but also for the policy makers, researchers, and educationists. Drawing from the "self-efficacy" theory (Bandura, 1977), the purpose of this paper is to explore the relationship between teacher self-efficacy and teacher effectiveness. In addition, it explores the role of collaboration among teachers and principal leadership in explaining the above relationship. Design/methodology/approach: Data were collected from 575 secondary school teachers and 6,020 students representing grade 6-12th from 25 privately owned schools in India. Teacher self-efficacy, collaboration and principal leadership were reported by the teachers whereas effectiveness of each teacher was captured from around ten students each who were taught by the corresponding teacher. Data were analyzed using SEM-PLS. Findings: Results confirmed a positive association between teacher self-efficacy and the three dimensions of teacher effectiveness, namely, teacher's delivery of course information, teacher's role in facilitating teacher-student interactions, and teacher's role in regulating students' learning. Results also confirmed that both collaboration and principal leadership are positively related to teacher self-efficacy. Originality/value: The results of the study indicate that schools need to focus on enhancing self-efficacy of their teachers and give importance to teacher collaboration and principal leadership in order to improve their effectiveness in terms of delivery of instruction, teacher-student interactions, and regulating student learning.