This account of infant observations on ‘average mothers and normal babies’ is a companion volume to On symbiosis and the vicissitudes of individuation. It studies mother-infant interaction when the children are between four to five months and three years old, and contains a wealth of information which repays study. It has been heralded as a milestone in psychoanalytic literature, so it challenges an assessment of this assertion.

Mahler's research was conducted in a small building and mothers brought their babies to it over prolonged periods (up to three years). The couples were relatively unselected and the project developed by ‘letting the mothers and babies show us the paths