<p>The year 2024 marks the 100th anniversary of cultural and historical psychology. Taking in consideration the growing demand for the ideas and positions of cultural-historical psychology in the world professional community started in 1978 and continues to this day, we have to highlight a number of emerging problems. Without the analysis of these problems it is impossible to further develop the theory itself. Firstly, it is the variety of interpretations and readings of the theoretical foundations of cultural-historical psychology that have emerged over the past decades. Secondly, it is the transformation of the conceptual apparatus of cultural-historical psychology into a "screen" for eclectic and purely empirical constructions of modern research aimed at studying the problems of the development and structure of consciousness and higher psychological functions. At the same time, it is possible to truly understand Vygotsky's concept only on the basis of an analysis of the genesis, content and interrelation of those concepts that make up the methodology of cultural-historical psychology. This article examines the concept of "sign", which is one of the key concepts in the cultural-historical concept of L.S. Vygotsky. The aim is to reconstruct the path that the author of cultural-historical psychology himself took in determining the place and role of this concept in the holistic theoretical and methodological structure of the concept he developed.</p>