From an evolutionary viewpoint, readiness to engage in appropriate behavior toward a recognized person seems to be inherent in the human brain. In support of this hypothesis, functional neuroimaging studies have demonstrated activation in regions relevant to relationship-appropriate behavior during the recognition of personally familiar (PF) people. Recognition of friends and colleagues activates regions involved in real-time communication, including the regions for inference about the other's mental state, autobiographical memory retrieval, and self-referential processes. Recognition of people related by romantic love, maternal love, and lost love induces activation in regions involved in motivational, reward, and affective processes, reflecting behavioral readiness for mating, caretaking, and yearning, respectively. The involvement of motor-associated cortices during recognition of a personal enemy may reflect readiness for attack or defense. Self-recognition in a body-related modality uniquely activates sensory and motor association cortices reflecting the sensorimotor origin of the bodily self-concept, with social cognitive processes being suppressed or context dependent. Issues and future directions are also discussed.