The process by which external, social interactions come to form the internal thoughts of an individual. That is, high level mental functions first exist on a social plane, before being absorbed into the child's mind through social interactions. This was discussed by [[Lev Vygotsky]] and expanded on by [[James Wertsch]] who attempted to understand the intermediate steps of internalisation. Internalisation is a foundational process that helps us understand the internal functionings of broader [[Sociocultural theory|sociocultural theories]] like [[Activity theory|activity theory]], [[Wiki/cards/Communities of practice|communities of practice]] and [[Actor-network theory|actor-network theory]].