A system and method for determining a user affinity for a category. The system calculates an affinity score based on a record of actions performed on the document by a user and a categorization of the document. This affinity score is computed by a weighted sum of factors associated with the document. The affinity score is normalized and a population threshold is applied. A predetermined percentage of the population of users associated with the document is determined and those users are said to have an affinity for at least one category assigned to the document. The system may also decay an affinity score if a user has not performed at least one action on the document. If the user performs an action on the document, however, the affinity may be reset. A user, system administrator or other user may also be enabled to decline an affinity for a category.