In this paper we study the adoption of Web 2.0 platforms. Existing theoretical approaches to understand the adoption of IT are critically re-examined for their applicability in the Web 2.0 domain. We find that the two basic assumptions of traditional approaches 1) the unit of analysis is a person and 2) the technology´s primary utility is personal, does not hold for Web 2.0 platforms. Instead, we argue, the appropriate unit of adoption is the social network and the utility stems mainly from collective use.