Vygotsky was interested in applying Marxist social theory to individual psychology. The approach he took to cognitive development is sociocultural, working on the assumption that 'action is mediated and cannot be separated from the milieu in which it is carried out' (Wertsch, 1991) He devised the sociocultural theory that subsequently influenced the development of the constructivist movement. (Jaramillo, 1996) Vygotsky's sociocultural theory of learning contends that intelligence in humans has its origins from within our society of culture. Individual cognitive advancement thus occurs first as interaction with one's social environment followed by interaction within oneself, e.g. internalization. (Brown, 1996) These two phases observed in classroom settings shows that the first phase of the cognitive process for students is when students encourage, support and guide each other while learning. This is followed by students forming their own conclusions based on the evidence they have observed and then resolve conflict by articulating their arguments. (Wertsch).

An important concept in Vygotsky's theory is that the potential for cognitive development is limited to a certain time span which he calls the 'zone of proximal development (Kearsley 1994). The zone of proximal development is defined as having four learning stages. These stages range from the lower limit of what the student knows and the upper limits of what the student has the potential of accomplishing. This seems to be very roughly analogous to concepts of intelligent quotients and testing in modern education.

Vygotsky's zone of proximal development is the zone in which students can solve problems collaboratively and learn from one another. Or stated a different way, students may be able to complete some tasks independently; never the less, in order for them to increase their level of potential development, students need to work with others. This collaborative zone stems from the idea that learning is social and happens when speech and activity come together. Knowledge does not originate from within us, according to Vygotsky, but instead we learn from our environment: when a student learns arithmetic or writing, he or she is internalizing external knowledge (Brown).