Objective: To compare the cognitive, social cognitive, behavioural, emotional and attachment security outcomes of children whose mothers were admitted to a psychiatric mother and baby unit (MBU) with those of offspring of mothers not admitted and with standardized norms. Method: Children aged 4-6 years of mothers admitted (following childbirth) to the dedicated psychiatric MBUs in Manchester, and still living with their mother, were traced for recruitment. Observational and multi-informant measures of developmental functioning were administered during a home visit. Results: From 94 consecutive admissions, 16 children participated and showed no poorer developmental outcomes than comparison children or standardized child norms. Girls, securely attached children and children of mothers with no current mental illness tended to show the most positive outcomes. Conclusion: Possible reasons for low participant recruitment are discussed. Our provisional findings suggest that interventions should focus on improving infant attachment security, targeted at women with psychotic and chronic illness, who have no partner and/or who have a male child.