This paper analyzes the origins and specificity of the recent research trend on the development in children of a Theory of mind which has undergone an impressive expansion over past the fifteen years. A comparison with Piaget's approach is proposed regarding the experimental data available on the coordination of perspectives as well as the epistemological foundations. The issues of the naturalization of the mind and its irreducibility are addressed within the framework of recent reductionist theories advanced by the philosophers of mind. Piaget's contribution is considered as one of the most thorough of this century.