This study was a survey research which was aimed to investigate the implementation of Web 2.0 technology for information literacy instruction (ILI) in Thai university libraries, in terms of information literacy skills being taught, types of Web 2.0 technology that were implemented, ways of implementing Web 2.0 technology, and problems in implementing Web 2.0 technology. Additionally, in case of the university libraries which did not apply Web 2.0 technology to their ILI, the research also explored their reasons, implementation plan, and factors important to their decisions on the implementation of Web 2.0 technology. A questionnaire responding to the research objectives was developed as the research instrument and it was distributed to collect the data from the library director/library head/library staff member who was responsible for ILI in all 127 Thai university central libraries. The research results are as follows: Generally, the majority of university libraries did not implement Web 2.0 technology for ILI. Concerning those implementing Web 2.0 technology for ILI, most respondents applied Web 2.0 technology to teach Standard 2: Accesses needed information effectively and efficiently. The type of Web 2.0 technology that most university libraries implemented was Social Networking. Also, most university libraries used almost every type of Web 2.0 technology for distribution of teaching content, news relevant to the instruction, and resource/information access to learners. Finally, they considered all four types of problems as quite problematic but the one receiving the highest mean score was problems relevant to operation. When problems relevant to operation were considered, one sub-problem was rated as very problematic while the rest were rated as quite problematic. The one rated as very problematic and received the highest mean score was the library did not have enough staff to implement Web 2.0 technology into ILI. Regarding the university libraries that did not implement Web 2.0 technology for ILI, most did not adopt it because they had a limited number of staff and existing staff already had a lot of works to do. In addition, the majority of them did not have a plan to implement Web 2.0 technology into ILI. Finally, they considered both internal factors and external factors as very important to the decisions on the implementation of Web 2.0 technology but, on the whole, internal factors received higher mean score. According to internal factors, all sub-factors were rated as very important but policy of the library administrators received the highest mean score.