130 Copyright © 2017, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited. Chapter 8 DOI: 10.4018/978-1-5225-1747-4.ch008 ABSTRACT This action research study was aimed at exploring how a collaborative e-mentoring platform can be used as a supplemental tool for professional teacher development, speciically on the issue of formative assessment practices. The platform consisted of a group of eight volunteer teachers working in loca- tionally disadvantaged areas and the mentors. Five modules were prepared and implemented based on the needs of the teachers, and the data were collected constantly from various sources throughout the study. The analysis of data revealed two basic themes: Positive aspects and challenges of e-mentoring. Overall, the study revealed that most of the teachers believed in the importance of having professional development support through e-mentoring because it could break down the locational barriers between teachers. Although there were some diiculties such as the unique problems or heavy workloads of the teachers, it still had implications for broader expressions for professional development. INTRODUCTION The World Education Report published by the United Nations Educational, Scientific and Cultural Or- ganization (UNESCO) in 1998 pointed out the importance of the teacher as an agent of change in the 21 st century, as reflected in the following lines: The need for change, from narrow nationalism to universalism, from ethnic and cultural prejudice to tolerance, understanding and pluralism, from autocracy to democracy in its various manifestations, and from a technologically divided world where high technology is the privilege of the few to a technologi- cally united world, places enormous responsibilities on teachers who participate in the moulding of the characters and minds of the new generation. (UNESCO, 1998, p. 16) E-Mentoring as a Professional Teacher Development Tool Muzafer Cetin Antalya International University, Turkey Sehnaz Sahinkarakas Çağ University, Turkey