Increasingly, mental health services are delivered through multidisciplinary teams and settings. This creates particular challenges for the development of evidence-based practice guidelines when different professional groups represented within teams might have different traditions and cultures in relation to what counts as ‘evidence’, and how that might be synthesized to produce guidance that supports best practice across professional divides. These challenges are explored in relation to integration between health and social care services, where social work in particular has traditionally expressed scepticism about guideline development where it does not incorporate knowledge drawn from qualitative research and perspectives of stakeholders such as service users and carers. This article takes the NICE-SCIE guideline on dementia care as an exemplar of how an integrated process of guideline development can deliver guidance for best practice across integrated mental health services. Finally, some of the issues still facing inter-professional guideline development are considered, and pointers given to eclectic approaches that are beginning to emerge from within social work.