During his ten-year period of systematic work in psychology, Lev Semenovich Vygotsky launched a series of investigations in developmental psychology, education, and psychopathology, many of which were interrupted by his untimely death. The Essential Vygotsky is a selection of the writings of Vygotsky (1896-1934), taken from the six volumes of Collected Works that have appeared both in Russian and in English translation. The editors have endeavored to choose the most important and most interesting contributions from all types of Vygotsky’s writings, and thus from all six volumes, so as to reflect the overall purpose of the program that Vygotsky was developing at the time of his early death. The introductory essays for each section explore various aspects of Vygotsky’s biography, in order to more clearly explain certain parts of his work and his writing. Vygotsky’s work has been influential not only among developmental psychologists, but has become increasingly important to other disciplines, such as anthropology and sociology, and in the application of psychology in such areas as education, human-computer interface design, and the organization of work.