The present article presents an understanding of beliefs as conceptualizing activity from a Vygotskyan dialectical perspective. The proposals I develop here, emerging from a contextual understanding of development, aim to help us reconsider in pedagogical terms the specific relationships between beliefs and actions and the nature of beliefs as dialectical language-mediated consciousness. Understanding beliefs as dialectical conceptualizations calls for rethinking teaching and learning as a developmental activity. It also illuminates a specific research methodology, semiogenesis, which captures the orienting power of beliefs as conceptualizing activity in the classroom. To illustrate a conceptual approach to beliefs as sociocultural tools of the mind, three basic examples of a conceptual task for in-service teachers are discussed.