Sociality defines human life. Our happiness and prosperity depend on our interaction with others. We need other people to help us learn and grow, to protect and guide us, to work and build with us, to find love and make meaning. However, the complexity of the social world also makes it challenging to navigate. To interact with others, we must understand their personality traits, momentary mental states, actions, relationships, and situations. My research investigates how the brain organizes social knowledge and uses this understanding to predict the social future. I use methods including fMRI, computational modeling, and naturalistic behavior to uncover the dimensions which structure our minds' maps of social space.