This book constitutes the refereed post-proceedings of the Third International Workshop on Engineering Self-Organising Applications, ESOA 2005, held in July 2005 as an associated event of AAMAS 2005. The 12 revised full papers and 6 revised short papers presented are organized in topical sections on novel self-organising mechanisms, methodologies, models and tools for self-organising applications, and specific applications of self-organising mechanisms.