From an evolutionary perspective, human relationships are shaped by multiple cognitive and affective mechanisms designed to solve long-recurring problems and opportunities faced by our ancestors. Different relationships—romantic, parental, friendship, acquaintanceship—differ in the threats and opportunities they afford. Because of this, the psychologies governing how people feel and think about different relationships differ profoundly as well: The psychology governing the feelings and thoughts people have about romantic partners is qualitatively different from the psychology governing feelings and thoughts about children, which is qualitatively different from the psychologies governing feelings and thoughts about friends, coworkers, and strangers. In this chapter, we review principles underlying an evolutionary psychology of relationships, and then focus on how fundamental social goals—self-protection, disease avoidance, affiliation, status, mate acquisition, mate retention, and kin care—shape how people think about, feel about, and engage in the wide range of relationships characterizing human social life.