Background: Specialist Mother and Baby Units exist for the admission of women with their babies, when a mother requires assessment and intervention because of mental illness or significant mental health difficulties. The promotion of the mother-baby bond has been a priority in MBU settings given that severe maternal mental illness can compromise this relationship. This service evaluation was conducted to explore which psychological and/or psychosocial interventions promoting mother-infant interaction were being offered to women admitted to Mother and Baby Units (MBUs) in the United Kingdom (UK) and to explore the measures used to assess the quality of the mother-infant relationship. Method: As part of this questionnaire-based survey, all 18 Mother and Baby Units (MBUs) in the United Kingdomwere contacted and asked to provide information on the psychological and psychosocial interventions currently being offered in their service to promote mother-baby interaction and, where applicable, the measures used to capture their benefits. Results: Sixteen (89%) MBUs completed the survey and provided information. The findings suggest that psychological and psychosocial interventions were offered in various ways, by different members of staff to mothers on their own orto mothers and their babies or the whole family unit, including the father. Conclusions: Although all of the 16 MBUs offered psychological and psychosocial interventions, the findingsindicatethe varied nature of intervention availability and application across MBUs in the UK, which may reflect the needs of the service user group each MBU caters for alongside regional variations and staff preferences and training backgrounds. Staff time, training and related costs were mentioned as obstacles for improved service delivery.