This work is a theoretical discussion about concept formation in a cultural-historical perspective that articulates Vygotsky’s system of concepts within Leontiev’s structure of activity. This effort has led to a theoretical proposition that we call concept-activity, a dialectical unity formed by a concept and its genetic activities, i.e., the systematised activities in which concepts emerge directed to a purpose. Taking volition and conscious awareness as analytic categories, we initially relate scientific concepts with actions — concepts-action — and everyday concepts with operations — concepts-operation. The articulation of these elements drives the emergence of conceptual thinking as an activity, framed by the term concept-activity. In o...