A method of classifying content items utilizes user-generated playlists. A content item is included in respective playlists from a plurality of respective distinct users. The method receives respective user-generated information corresponding to the content item from each of the respective distinct users. For some users, the respective user-generated information is the respective playlist title. For other users, the user-generated information is the text of social network posting that identifies a respective playlist. In each case, the respective user-generated information specifies a first content item attribute that characterizes the content item. Accordingly, the method assigns the first content item attribute to the content item. Subsequently, a request is received from a first user for a content item having the first content item attribute. In response, the method selects the content item according to the first content item attribute and delivers the first content item to the first user.