This document discusses the application of Lev Vygotsky's sociocultural theory to second language acquisition (SLA). It outlines two key concepts from Vygotsky's theory - that social and cognitive processes are interrelated, and the zone of proximal development (ZPD). Regarding the first concept, social interaction plays a fundamental role in cognitive development. Learning occurs through transforming external social processes into internal cognitive processes. Regarding the ZPD, it represents the gap between independent problem-solving and problem-solving assisted by a more capable peer, and provides the conditions necessary for learning. The document analyzes how these concepts can be applied to interpreting SLA research and minimizing the gap between learners' first and second language proficiencies