Evolutionary psychology (abbreviated ev-psych or EP) is a theoretical approach to psychology that explains many mental traits as adaptations in the sense of evolutionary biology, as a product of natural or sexual selection. This is to bring the functional way of thinking about biological mechanisms, such as the heart or the immune system, into the psychological field, and to approach psychological mechanisms, such as perception or language acquisition, in the same way.

Though applicable to any organism with a nervous system, most research in Evolutionary Psychology focuses on humans. Specifically, Evolutionary Psychology most strongly supports the Massive Modularity hypothesis, which proposes that the human brain comprises many functional mechanisms, called psychological adaptations or evolved psychological mechanisms (EPMs), that evolved by natural selection. Uncontroversial examples of EPMs include vision, hearing, memory, and motor control. More controversial examples include language acquisition modules, incest avoidance mechanisms, cheater detection mechanisms, and sex-specific mating preferences, mating strategies, and spatial cognition. Most evolutionary psychologists argue that EPMs are universal in a species, excepting those specific to sex or age.

Evolutionary psychology has roots in cognitive psychology and evolutionary biology. It also draws heavily on behavioral ecology, artificial intelligence, genetics, ethology, anthropology, archeology, biology, and zoology. Evolutionary psychology is closely linked to sociobiology, but there are key differences between them including the emphasis on domain-specific rather than domain-general mechanisms, the relevance of measures of current fitness, the importance of mismatch theory, and psychology rather than behaviour. Many evolutionary psychologists, however, argue that the mind consists of both domain-specific and domain-general mechanisms, especially evolutionary developmental psychologists. Most sociobiological research is now conducted in the field of behavioral ecology.

The term evolutionary psychology was probably coined by Ghiselin in his 1973 article in Science. Jerome Barkow, Leda Cosmides and John Tooby popularized the term in their highly influential 1992 book The Adapted Mind: Evolutionary Psychology and The Generation of Culture. Evolutionary psychology has been applied to the study of many fields, including economics, aggression, law, psychiatry, politics, literature, and sex.