Educators and psychologists alike pay lip service to the interrelatedness of learning and development. Vygotsky was a leading Marxist theoretician in the early years of the newly formed socialist state, the Soviet Union. Vygotsky's method is dialectical rather than dualistic. It is activity-based rather than knowledge and epistemology-based. Vygotsky's leadership in restructuring psychology, education, and culture in the service of what was hoped would be a new kind of society was abruptly halted. Vygotsky's concern with learning and development both informed and was informed by investigations of specific psychological processes presumed in instructional practices designed for the learning of scientific concepts, foreign languages, speaking, writing, and concept formation. Vygotsky's critique of Piaget helps us to see how the dichotomies perpetuated by educational and developmental psychology were produced. Whereas most of Vygotsky's investigation of the Zone of Proximal Development (ZPD) concerns learning and instruction in schools, it is his analysis of the ZPD of the language-learning young child.