The Troubled Families Programme: Learning about policy impact through realist case study research.

This article aims to critically explore how qualitative case study research that is founded on realist principles can fundamentally enhance social policy evaluation methodologies and, in turn, provide improved learning for policy makers and practitioners. We suggest that these methodological advantages are accrued through the careful construction of theory‐based explanations of "how" policy programmes work thereby addressing the limitations of quasi‐experimental methods—namely, a focus on and prioritisation of outcome measures. The paper situates this key argument within wider, long‐standing debates about evidence‐based policy making and what constitutes "evidence" of impact in social policy. It does so through reflection on the contentious and contradictory knowledge claims that surround the Troubled Families Programme and evaluative claims regarding its efficacy. In conclusion and looking forward, we suggest that there remains much scope to combine "intensive" qualitative case studies with "extensive" quantitative measures within local and national evaluations of complex, multidimensional social policies, such as the Troubled Families Programme. [ABSTRACT FROM AUTHOR]