Since the 1980s, international commentators have debated extensively the impact of neoliberal reform agendas that have sought both to reduce the influence of planning and to make policies and practices more responsive to market processes. This reform agenda has been particularly evident in the context of planning for housing, where in many countries, the clamour for greater deregulation of land and housing markets continues apace. For example, in the UK the Coalition Government appointed a Planning Minister in September 2012 who had openly revealed that not only did he see little value in planning, but by extension, provided considerable evidence that he appears to accept - as do his colleagues in government - that the planning system merely prevents the market from delivering economic growth. As Nick Boles commented in 2010:Do you believe that Planning can work? ... I believe it can't work, David Cameron believes that it can't work, Nick Clegg believes that it can't work. Chaotic, in our vocabulary, is a good thing. (Ipsos MORI debate, Westminster, December 2010; available to view at www.guardian.co.uk/politics/2010/dec/18/coalition-local-planningboles-chaos)He went on to suggest that it was both impossible and undesirable to attempt to predict or control urban development.There would be little point in this Special Issue if we were to agree with these views. They obviously represent an extreme and very simplistic position, but they do help to underscore the context for this themed issue. The issue is motivated by the fact that the primacy given to the market, and the extent to which this is driven by economic motives, has seen debates about planning for housing come to be dominated by 'economists', by which we mean academics, researchers and commentators whose analyses are based on largely quantitative forms of economic thinking. Thus, it has been economists who have provided the evidence about the negative impacts of planning on the housing system and the wider economy; about the ways in which planning processes fail to account adequately for the structure of markets; and about the failure of planners and their policies to identify and respond to the price signals that emerge in local markets. In recent years, it has been professional economists within government departments who have been setting the research questions, designing the project briefs and driving the methods of investigation used to develop the evidence base for policy. It has also largely been economists that have been conducting the research, interpreting what are often highly codified findings, and transmitting the messages to policy makers. Depressingly, planners and other social science researchers have tended to be excluded from this process and these key debates: they simply do not speak the right language to have been able to contribute to a largely economics-dominated research and policy formation agenda.The purpose of this Special Issue is twofold: first we seek to showcase some of the rich applied research that can be used to shed light on how we might better plan for housing, and second we hope to demonstrate the ease with which the richness of academic findings can be lost in translation between the research community, policymakers and political pronouncements of the sort presented above. Thus this editorial and the contents of this issue are intended to provide a less codified introduction to key debates about the interaction between planning and the housing system, and they seek to illustrate the importance of framing debates about the relationship between planning and the housing system within a range of evidence bases that should include, but also transcend, the current economic orthodoxy. Here, we suggest that our contributors help encourage a more nuanced take on the assertion that planning constrains markets to an unacceptable degree. We go on to argue that the contributions also help to explore the challenges associated with dealing with the spatiality of markets and illustrate some of the problems associated with monitoring the dynamics of complex (and not fully marketised) housing systems. …