Measurements of change in family functioning during admission to the In-Patient Families Unit at the Cassel Hospital were devised, defined, and used to compare 14 families who were seen to make beneficial changes in their functioning as a result of in-patient treatment with 14 families who were not seen to make such a change during admission. Current family circumstances, the background histories of mothers, the quality of mothers' relationships remembered, observed, and established during admission, and other independent measures of change were significantly different between the two groups. The quality of ‘internal object relationships’ was identified as an important indicator of a capacity to benefit from treatment in this setting.