Web 2.0 tools and applications (e.g., blogs, wikis, forums, RSS, podcasts and videocasts) as well as social markers (e.g., Del.icio.us, Technorati, Facebook and Digg) have reached government and commerce sites; however, there is still a dearth of research related to the adoption levels of such tools. The purpose of this research is to contribute toward filling this gap by assessing the impact of this trend on Mexican local government sites by asking the following question: to what extent have local e-Government websites in Mexico adopted Web 2.0 tools and applica- tions? To answer this question, the paper starts by reviewing key concepts of Web 2.0 applications in government portals. On the basis of a longitudinal evaluation of Mexican local government sites, we found that most of the websites analyzed have increased their use of Web 2.0 tools and applications; however, we also found that not all applications are equally well-developed or used on the local websites. Web 2.0 is only in the initial stages of adoption in Mexican government websites.