This mixed-method study explores the views of professionals and service users with regard to Maternity Drugs Service provision in Bristol, UK. Findings indicate that this specialist multidisciplinary service, in many ways, can be seen as a model of good practice. Effective multi-agency and multidisciplinary working; early engagement; a service-user-centred approach; positive and non-judgemental staff attitudes contribute to good maternal and child outcomes. However, this service also experiences challenges arising from unclear management structures, differing work practices, and staffing levels. Consistency and clarity within and across complex services, and continuous service development are identified as necessary to effectively meet the needs of an extremely vulnerable population.