Considering most psychological disturbances of young children as ''rel
ationship disturbances'', the diagnosis is not applied to the infant a
lone, but to the parent-infant relationship. We also systematically co
nsider that it is the relationship which needs to be treated. The conc
ept of the infant as therapist appeared to us within the practice of c
onjoint mother-infant psychotherapy. It refers to the role of the infa
nt as incarnating and acting at the level of behaviours inner conflict
s of the mother. As such, the infant is like an actor who dramatizes i
n concrete ways the mother's psychic reality. He becomes a co-therapis
t in as much as he contributes to a process of representations of the
mother's inner reality. The concept is illustrated by two clinical exa
mples.