The study explores the mediating effect of teacher's empowerment on the relationship between instructional leadership (IL) to teacher's organizational citizenship behavior (OCB) toward student, team-members, and school. 395 Israeli teachers completed PIMRS, SPES, OCB, and demographic questionnaire. Path analysis showed a good fit of the data to the theoretical model. Teacher's empowerment is a partial mediator for OCB toward student and school; and a full mediator for OCB toward team-members. Teacher's OCB is crucial for schools' effectivity, therefore identifying empowerment as a full mediator for OCB toward team-members may assist improving teamwork, especially through IL.