This paper addresses the causal impact of being raised in a sole-parent family on child well-being across the OECD. The question is answered by a cross-OECD meta-analysis and a literature review. The overall conclusion is that the literature on the effects of sole parenthood on child well-being, while extensive and growing in sophistication, lacks a clear consensus on the existence of a causal effect. That any such effect is small is a conclusion which can be asserted with more confidence. There is enough in the literature to suggest policy makers should be concerned about the implications of family structure for child well-being. Policy makers should keep a close eye on social trends in terms of changes in family structure, as well as on the developing research literature on the impact of family structure on child well-being. However, there may not be enough in the literature yet, in the absence of extra-scientific priors, to advocate radical policy change, especially if levers to change family form are costly to undertake or uncertain in effect. What should be clear from this review is that this is an area of social science which is rapidly expanding. It may well be that in another decade research will cast a more certain light on the questions addressed here.