The World-Wide Web (WWW) is an extremely effective mechanism for sharing information throughout the world via a web of links. These links allow anyone with a connection to the Internet to unearth large amounts of information on multitudes of topics. However, access to this information is asynchronous, with no way for users to interact with each other in real time. We have developed Neighborhoods to support synchronous interaction between users. Related documents can be grouped together into a Neighborhood, which acts as a meeting place where Web users can find and contact others with similar interests. Neighborhoods are based on underlying protocols for creating collections of documents and for establishing collaborative sessions. The collection protocol allows material on the Web to be organized into categories and subcategories, providing context and a readable graphical representation of a set of related documents. The Neighborhoods protocol adds to this a method for specifying and establishing new collaborative sessions, as well as locating existing ones.