Mendeley is a free, web-based tool for organizing research citations and annotating their accompanying PDF articles. Adapting Web 2.0 principles for academic scholarship, Mendeley integrates the management of the research articles with features for collaborating with researchers locally and worldwide. In this article the features of Mendeley are discussed and critiqued in comparison to other, similar tools. These features include citation management, online synchronization and collaboration, PDF management and annotation, and integration with word processing software. The article concludes with a discussion of how a social networking tool such as Mendeley might impact the academic scholarship process.