People constantly make inferences about others' beliefs and preferences. People can draw on various sources of information to make these inferences, including stereotypes, self‐knowledge, and target‐specific knowledge. What leads people to use each of these sources of information over others? The current study examined factors that influence the use of these sources of information, focusing on three interpersonal dimensions – the extent to which people feel (a) familiar with, (b) similar to, or (c) like the target. In four studies (total N = 1136), participants inferred the beliefs and preferences of others – celebrities (Studies 1a–1b), constructed fictional targets (Study 2), and actual acquaintances (Study 3). Participants also rated familiarity with, similarity to, and liking of the target. Analyses assessed the use of each source of information by comparing inferences with information provided by those sources. Familiarity was associated with greater use of target‐specific knowledge, while similarity and liking were associated with self‐knowledge. Low similarity and high liking were associated with increased use of stereotypes. We discuss the implication of these findings and their applicability to unique cases, including inferences about celebrities, public figures, and positively stereotyped groups, in which familiarity, similarity, and liking do not perfectly align.