In unstructured interactions, male friends were found to be more accurate than male strangers in inferring each other's thoughts and feelings. Plausible reasons for this difference were that friends (a) interacted more and exchanged more information, (b) had more similar personalities and therefore more rapport with each other, and (c) had more detailed knowledge of each other's lives. Data confirmed that the friends did indeed interact more and were more similar in their sociability than the strangers; however, these differences did not account for the friends' greater empathic accuracy. Instead, this was primarily attributable to a difference in knowledge structures, namely, the friends' ability to accurately read their partners' thoughts and feelings about imagined events in another place or time.