The main purpose of this volume is to offer evidence of the contributions made by teachers, students, researchers, and administrators to classroom research and to the overall educational process. To this end, the editors explore four major themes: (a) research carried out by teachers and teacher educators of direct benefit to teachers; (b) professional development based on the analysis of diverse classroom phenomena; (c) collaboration of learners with teachers, teachers with teachers, and teachers with teacher educators; and (d) different language education contexts (research sites in seven countries on three continents), from which the editors seek common features in the traditional distinction between so-called foreign, second, and modern language education.