The chapters in this volume summarise and integrate the results from a series of research reviews funded by the Nuffield Foundation in the late 2000s, with a view to shedding light on what we do and what we do not know about some key changes in the lives of young people over the last three decades in the UK, and the relevance of these changes for symptoms of mental health. The work has brought together a range of topics that are not normally considered in the round. It aimed to test what we knew in the way of substantive findings across these topics, and also to set an agenda for further research.

It is not easy to chart a clear line through the various results and non-results that we uncovered. We want to make some general points, and highlight some specific implications arising from particular topic reviews. Some counter-intuitive facts are interesting in their own right. There is, however, a need to remember what we can and cannot say with these kinds of data. First, the extent of information available was, we found, often surprisingly limited, even at the basic descriptive level. This was itself an interesting finding, given the strident assertions in the general media and by various stakeholders about how things have changed for young people. Second, although we started with work showing clear time trends in adolescent mental health, it seems clear that the implications may be different for different groups of adolescents. Yet very little work in our selected topics focused on group comparisons, showing how different subgroups of young people diverge in their experiences. In this chapter, then, we reflect on some of the broader implications of the work as a whole for our thinking on social structures and young people's everyday experiences, given these two limitations. Of course more research is needed, as all researchers almost invariably conclude, and this chapter will make some concrete suggestions about where we need to know more. But we also think that some issues are clear enough to warrant some substantive observations, or at the very least some hypotheses that might usefully inform public discussion. We have tried to be clear where these are more or less firmly founded.