Željko Trezner is active in different projects, expert councils and groups in the field of tour operator and travel agency management, destination marketing/management and sustainable tourism in general. He teaches at VERN’ University in Zagreb and University College Aspira in Split. He is Counsellor of the Association of Croatian Travel Agencies Board of Directors and Director of the Centre for Responsible Tourism in Karlovac. As an expert with the business background he has successfully merged theoretical thesis into practical solutions published in numerous manuals and professional papers and presented at many workshops, seminars and conferences in Croatia and abroad.