L.S. Vygotsky (1896-1934) a man of many talents, who is famous mainly as a psychologist. His works written between 1924-1934 do not belong to history. The influence of his ideas on modern psychology and education is only growing. The importance of his cultural-historical approach is widely accepted today particularly because the most influential twentieth century approaches to Psychology failed to recognize the vital role of cultural and social environment and the mediating function of adults in the learning process and cognitive development of the child. The book "Language and Thought" was published in Russian in 1934 shortly after Vygotsky's death and the first translation into English came only in 1962. Today it has been translated into more than twenty languages. In the present Hebrew complete translation from the original Russian a special effort has been made not only to precise in transmission of the content, but also to preserve the style and the distinctive thought process of the author. In this book Vygotsky gives a thorough critical analysis of the theory of Jan Piaget. The Hebrew edition includes the response of Jan Piaget, written about thirty years later. The book includes also Vygotsky's article on childhood bilingualism as this subject matter is of particular relevance and importance in the context of Israel. The book contains a preface "The Riddle of Vygotsky" by the scientific editor of the Hebrew translation Dr. Bella Kotik-Friedgut. The author explains the importance of Vygotsky's ideas for modern education. The introduction provides acquaintance with the many and varied accomplishments of Vygotsky's brief life as a man, a scientist and as a Jew.