Background: Care for clients with mental health problems and concurrent intellectual disability (dual diagnosis) is currently expected to be provided through the care programme approach (CPA), an approach to provide care to people with mental health problems in secondary mental health services. When CPA was originally introduced into UK mental health services in the 1990s, its implementation was slow and problematic, being hampered in part by problems occurring at a strategic level as health and social service organizations attempted to integrate complex systems. This article reports on a study of a more recent attempt to implement CPA for dual diagnosis clients in one mental health foundation trust, aiming to gauge progress and identify factors at the strategic level that were helping or hindering progress this time round. Methods: The study took place in a mental health National Health Service (NHS) Foundation Trust in a large English city, which was implementing a joint mental health and intellectual disability CPA policy across five of its constituent boroughs. Semi-structured interviews with key informants at Trust and borough levels focused on the Trust's overall strategy for implementing CPA and on how it was being put into practice at the front line. Documentary analysis and the administration of the Partnership Assessment Tool were also undertaken. Data were analysed using a framework approach. Results: Progress in implementing CPA varied but overall was extremely limited in all the boroughs. The study identified six key contextual challenges that significantly hindered the implementation progress. These included organizational complexity; arrangements for governance and accountability; competing priorities; financial constraints; high staff turnover and complex information and IT systems. The only element of policy linked to CPA that had been widely taken up was the Greenlight Framework and Audit Toolkit (GLTK). The fact that the toolkit had targets and penalties associated with its implementation appeared to have given it priority. Conclusion: None of the contextual challenges identified in this study were specifically related to CPA as a policy or to the needs and circumstances of dual diagnosis clients. Nevertheless, they inhibited the types of organizational change and partnership working that implementing CPA for a client group of this kind required. Unless these more generic factors are acknowledged and addressed when introducing policies such as CPA, the chances of effective implementation will inevitably be compromised.