This book constitutes the refereed proceedings of the Third International Conference on Trust Management, iTrust 2005, held in Paris, France in May 2005. The 21 revised full papers and 4 revised short papers presented together with 2 keynote papers and 7 trust management tool and systems demonstration reports were carefully reviewed and selected from 71 papers submitted. Besides technical issues in distributed computing and open systems, topics from law, social sciences, business, and psychology are addressed in order to develop a deeper and more comprehensive understanding of current aspects and challenges in the area of trust management in dynamic open systems.