Abstract: Elements to be provided for display with an instance of content can be determined dynamically based upon features of those elements. The actions or behavior of a user can be stored over time, and used to determine element features that are of interest to the user for various categories of content. In order to obtain enough data for multiple categories, clustering of users can be performed where users with similar behaviors are grouped together, and their preferences for features determined for various categories. When a request for content is received, a category and user identity can be determined for the request, which is used to determine the appropriate cluster. The feature preferences for that cluster can then be used to select elements (e.g., images, audio, or video) to present with the content based at least in part upon the relevant features of those elements.