This book opens with a short presentation of the principles of adult education and the innovative in-service training program Synergy. It presents the results of continuous evaluation for the first 10 years that the program was in implementation and the results of final evaluation, as seen from the replies of trainees and educators – mediators who took part. It shows the effectiveness of Synergy in terms of pedagogical groups, pedagogical practices and personal professional development for all parties involved and suggests ideas on how to improve and promote this proven, successful practice.