What will they think of next? The contemporary colloquial meaning of this phrase often stems from wonder over some new technological marvel, but we use it here in a wholly literal sense as our starting point. For millions of years, members of our evolving species have gazed at one another and wondered: what are they thinking right now . . . and what will they think of next? The interest people take in each other’s minds is more than idle curiosity. Two of the defining features of our species are our behavioral flexibility — an enormously wide repertoire of actions with an exquisitely complicated and sometimes non-obvious connection to immediate contexts — and our tendency to live together. As a result, people spend a terrific amount of time in close company with conspecifics doing potentially surprising and bewildering things. Most of us resist giving up on human society and embracing the life of a hermit. Instead, most perceivers proceed quite happily to explain and predict others’ actions by invoking invisible qualities such as beliefs, desires, intentions, and feelings and ascribing them without conclusive proof to others. People cannot read one another’s minds. And yet somehow, many times each day, most people encounter other individuals and “go mental,” as it were, adopting what is sometimes called an intentional stance, treating the individuals around them as if they were guided by unseen and unseeable mental states. In this chapter we consider how perceivers mind-read, how well they do this task, and how mind perception comes to life in a number of important domains, such as intergroup relations and interpersonal conflict.