The paper analyzes several ideas from the works of AN Leontiev and reflects upon the effects of these ideas on the development of general psychology and in particular on the understanding of animal and human behav ior through the concepts of activity, perception and motivation processes, voluntary regulation. Thus, the paper analyzes the concept of'sensory experience'and the role of activity in transforming experiences into senses; discusses Leontiev's contribution to the understanding of motivation in terms of his introduction of the concept of an object of need and his new interpretation of the motive of activity; analyzes the role of the con cept of meaning in creating a temporary derivative of goal valence and in voluntary self regulation. Finally, the paper explores the connection between the ideas of Vygotsky and Leontiev and the relationship between cul tural historical psychology and Leontiev's activity theory.