Learning and instruction have always been important topics in the sociocultural school of thought founded by Vygotsky and further developed by his followers. Taking sociocultural ideas as a starting point, Piotr Galperin developed an original conceptual system and a new method of investigation that made teaching and learning a central part of psychological research. We analyze Galperin's theory and discuss its direct relevance for educational practice. The analysis is based on a spiral model that, we suggest, most adequately represents Galperin's procedure of the formation of mental actions. This model helps to clarify the relevance of Galperin's approach to current issues in psychology and education.