Proceedings of European Business Research Conference Sheraton Roma, Rome, Italy, 5 - 6 September 2013, ISBN: 978-1-922069-29-0 Supporting Factors and Barriers in Sustainability Report Assurance: The Case of Thailand Setthasakko Watchaneeporn* and Thungkatikajonkit Pornpiroon** This study examines supporting factors and barriers in the sustainability report assurance by conducting in-depth interviews with 4 assurance providers and 4 client companies regarding the assurance engagement in Thailand. It is found that coordination between assurance providers and clients, assurance providers’ knowledge, and clients’ management sponsorship positively influence the assurance process. The findings also suggest that assurance providers’ insufficient experience, clients’ unsettled management system, tight period of time in assurance, obscure Sustainability Report framework, and language barriers negatively affect the assurance process. In addition, the findings point out that the lower barriers in assurance process are, the more efficient the assurance process will become. Field of Research: Accounting Key Words: Sustainability Report Assurance, Barriers, Supporting Factors. *Setthasakko Watchaneeporn, Thammasat Business School, Thammasat University, Thailand . Email : wsetthasakko@yahoo.com **Thungkatikajonkit Pornpiroon, Thammasat Business School, Thammasat University, Thailand . Email: pearando_2628@hotmail.com