Activity Theory (AT) is a psychological and philosophical framework originating from the work of Vygotsky, Leont’ev, and later Engeström. It conceptualizes human activity as a hierarchical system composed of activities (driven by motives), actions (directed at goals), and operations (automated routines). Engeström’s third-generation AT introduces the concept of an activity system — a collective unit of analysis comprising subject, object, tools, rules, community, and division of labor. AT is widely used in CSCW, HCI, organizational learning, and educational research to analyze collaborative work practices and contradictions within systems. It is particularly relevant in Education, Software Engineering, Social Sciences and Healthcare.

Activity Theory supports co-production, interdisciplinary and community-based collaboration and is suited for small teams, organizational settings and community-scale initiatives in in-person, remote and hybrid settings.

Activity Theory is classified as a well-documented framework, indicating broad adoption and available documentation. Key concepts include Activity system, Mediation, Zone of proximal development, Contradictions.