1. A computer-implemented method comprising: obtaining, by a computer system, information that identifies viewing activity of users with regard to content that is associated with social network profiles, wherein the viewing activity identifies content that the users have viewed; identifying, by the computer system, a portion of the social network profiles, associated with a first group of users, that include a particular category of content; assigning, to the portion of the social network profiles, initial scores that indicate that the portion of the social network profiles include the particular type of content; determining, by the computer system, viewer scores for the first group of users based on i) the viewing activity of the first group of users and ii) the initial scores that are assigned to the portion of the social network profiles; determining, by the computer system, content scores for each user in a second group of users in a remaining portion of the social network profiles based on, for each user in the second group, i) the viewing activity of a particular user in the second group of users, ii) the viewer scores for the first group of users, and iii) a weighting value that indicates a closeness of a relationship between the particular user in the second group of users and a particular user in the first group of users; and selecting, by the computer system and based on the content scores, one or more users in the second group of users in the remaining portion of the social network profiles as having at least a threshold likelihood of including the particular category of content.