The zone of proximal development (ZPD) is defined as an overarching concept that integrates the main tenets of Vygotsky's theory of human development. The conceptualization of the ZPD begins with its social, cultural, and historical context and traces its development as a spatial and temporal metaphor that reflects the sociogenetic root of all human mental functioning. Beyond the explication of sociogenesis, the ZPD is reconceptualized to include the notions of voice and dialogicality. The insights gained from the fields of semiotics and discourse studies allow a broader understanding of the ZPD by bringing to light participant structures and institutional and historical forces that may not have been included in the dominant interpretations of the ZPD.