Web 2.0 refers to an emerging social environment that uses various tools to create, aggregate, and share dynamic content in ways that are more creative and interactive than transactions previously conducted on the Internet. The extension of this social environment to libraries, sometimes called Library 2.0, has profound implications for how librarians will work, collaborate, and deliver content. Medical librarians can connect with present and future generations of users by learning more about the social dynamics of Web 2.0's vast ecosystem, and incorporating some of its interactive tools and technologies (tagging, peer production, and syndication) into routine library practice. doi: 10.1300/J115v26n01_01.