Cultural-historical activity theory (CHAT) is a theoretical framework which helps to understand and analyse the relationship between the human mind and activity. It traces its origins to the founders of the cultural-historical school of Russian psychology L. S. Vygotsky and Aleksei N. Leontiev. Vygotsky's important insight into the dynamics of consciousness was that it is essentially subjective and shaped by the history of each individual's social and cultural experience. Especially since the 1990s, CHAT has attracted a growing interest among academics worldwide. Elsewhere CHAT has been defined as "a cross-disciplinary framework for studying how humans purposefully transform natural and social reality, including themselves, as an ongoing culturally and historically situated, materially and socially mediated process". Core ideas are: 1) humans act collectively, learn by doing, and communicate in and via their actions; 2) humans make, employ, and adapt tools of all kinds to learn and communicate; and 3) community is central to the process of making and interpreting meaning – and thus to all forms of learning, communicating, and acting.

Lev Semyonovich Vygotsky was a Russian and Soviet psychologist, best known for his work on psychological development in children and creating the framework known as cultural-historical activity theory. After his early death, his books and research were banned in the Soviet Union until Joseph Stalin's death in 1953, with a first collection of major texts published in 1956.