A method for determining behavior-based relationships between website users is provided. The method may include monitoring activity of a plurality of users of a website to collect data regarding interaction with one or more content items associated with the website by the plurality of users. The method may further include analyzing the collected data to determine one or more relationships among the plurality of users based at least in part on the interaction with the one or more content items by the plurality of users. The method may additionally include generating a behavior graph having a structure defined based at least in part on the determined relationships. A corresponding system, apparatus, and computer program product are also provided.