In the present overview of research on certain aspects of psychologica
l functioning (such as language, perception, explanation of actions, a
ppearance/reality, etc.), the development of children's representation
s of the mental functioning of human beings is described. Children at
a very early age appear to have already acquired knowledge about the h
uman mind and constructed representations of it. These allow them to d
ifferentiate between mental and physical entities, attribute various m
ental states to human beings, and explain human actions in terms of me
ntal states such as desires and beliefs, etc. However, at approximatel
y 5 years old, important qualitative changes take place in the represe
ntation children have of mental life. Their prior conception of the hu
man mind as a reservoir of mental states (resulting from direct contac
t with reality) is replaced by a conception of the mind as a mediator
and, thus, a generator of mental states.