This article analyzes the theories of cognitive development developed by J. Piaget and L.S. Vygotsky from the perspective of modern psychology. The study examines the main ideas of these theories, their similarities and differences, as well as their contemporary scientific interpretations. Furthermore, the significance of these theories in explaining cognitive development in modern psychology is highlighted. The findings indicate that the integration of Piaget’s and Vygotsky’s perspectives provides a deeper understanding of individual development.