This chapter traces the origins of the idea in Lev Vygotsky's thought in the early 1930s. The notion of zona blizhaishego razvitia ZBR had great promise for developmental psychology and education. For Vygotsky, the use of the ZBR concept was descriptive rather than explanatory. Vygotsky perceived the process of imitation as the mechanism of development. Vygotsky developed the idea of heterochronic emergence of different psychological functions. It is interesting that the origin of the notion of the zone of proximal development (ZPD) can be found in Henri Bergson's thinking. The ZBR-in the form of the ZPD-is assumed to exist as an entity among other psychological functions (e.g. cognitive characteristics). Its focus on the dynamic process of emergence has become translated into a static depiction of some process of teaching and learning-usually with the focus on the relevance of the "more experienced" partner in the educational interaction.