The promotion of diversity formed a major plank of police reform during the late 1990s and into the 2000s. A plethora of policy statements, training programmes, recruitment drives, organizational investment, and community engagement activity followed a series of authoritative reports, culminating in the 1999 Macpherson Report. However, perhaps the nature of public debate and the cyclical nature of policy reform contributed to a subsequent sense that the ‘diversity agenda’ was complete, that the police service had ‘done diversity’, and that other priorities required attention. A key proponent of the immediate post-Macpherson reform, Jack Straw had moved from the Home Office and was Justice Secretary when, in 2009, he stated that the Metropolitan Police was no longer institutionally racist. Since then policing in the UK, and elsewhere, has faced huge challenges in terms of spending cuts that have both impacted on police budgets as well as those of other agencies dealing with marginalized and vulnerable communities. In that context, it has been understood that the promotion of diversity has become an unaffordable liberal preoccupation that has to be swept aside by the cold winds of austerity. In that—rather bleak—context the publication of a special edition devoted to issues in police diversity might seem incongruous. Contrary to some prevailing opinion, however, we argue that there are a number of reasons why the importance of diversity within policing needs to be re-stated. First, as the papers gathered here indicate, there continues to be a wide range of investment in programmes to promote diversity in the UK, in Europe, and in the USA. Incomplete, partial, and with varying degrees of success, but the promotion of more inclusive, more effective, and more legitimate police services that better reflect the diversity of contemporary global societies, continues. Secondly, as the contributions in this collection reaffirm, the development of a more diverse policing can secure a range of operational and institutional advantages to police services. In an era in which financial austerity and changing demand on police services have increased focus on the development of evidence-based policing, the research represented here (and the much wider body of literature available in general) can be used to help generate policy relating to diversity that will enhance the delivery of contemporary policing. Thirdly, diversity within policing is of continuing importance in terms of the promotion of professionalism, ethics and integrity, and public legitimacy. Although none of these related factors were