This Middle East-based study enquires how peer mentoring might enhance professional development of EFL teachers and affect student leaming. Research covering 1999 to 2003 developed my intial peer mentoring initiatives of 1997 and 1998.1 adjusted to various professional roles within three settings. I was supervisor of EFL training, from 1997 to 2001, observer of an RSA Celta teacher training course at the British Council, from February to April 2001 ( interacting between September 2001 and May 2003 with some course participants in their first EFL jobs) and from 2001 onward teacher/coordinator of Social Studies in an English - medium international school attempting curriculum change. Mentoring roles varied accordingly. The action research is interventionist and the methodology leans heavily on the ethnographical approach which contains thick description and analysis of questionnaires, interviews, constructed pro-formas and diary notes. As an insider researcher in the three settings, I have been able to follow closely a process of peer mentoring trials. Highlights of the results are that interactive work that draws on the total experience of the teaching staff of an institution can lead to new implementations in the EFUESP classroom and in curriculum development; that 'traditional' mentoring can lead to a 'monologic' process rather than open dialogic learning; that defined curricula, hierarchical management structures and teachers' own natural defensive attitudes create a climate of non-responsiveness to change. Management does not draw on the total experience of teachers. Students, however, seem to value a perceived collaborative stance by teaching staff. Peer mentoring appears to shift the emphasis from a defined body of subject knowledge and one specific training to skill sharing in the workplace and to balancing pedagogic knowledge with subject knowledge and combining strengths offered by non - native - speaking and native - speaking teachers. Peers can also benefit through interactive use of the internet. The research suggests that international schools and EFL institutions become more responsive to the latent dynamism that exists within their staff and that they hire trained peer mentoring facilitators to promote effective collaboration.