The reforms that followed the socio-economic crisis which unfolded in 2008 should not be considered as completely new, but rather as the acceleration of a longer trend in educational change (Ball, Maguire, and Goodson 2010). However, the scale of the transformations leads us to question whether the crisis might represent a turning point leading either to the intensification of market reforms or to their weakening as part of a wider reassessment of the links and tensions between inequalities, economic performance and taxation (Carpentier 2012). Stephen Ball is one of the key scholars who have explored the origins of these educational transformations and examined their implications for pupils, students, the educational workforce and the wider society. His policy cycle approach (Ball 1994; Bow, Ball, and Gold 1992) led him to develop research in key interconnected areas of education policy which are more than ever relevant to the understanding of the current context. These include the relationships between the intersected inequalities (in terms of social class, gender and 'race') in societies and access and participation in education (Ball 2003a; Gillborn 2008; Reay, David, and Ball 2005; Vincent et al. 2013); the policies related to choice (Ball and Vincent 1998), marketisation and privatisation (Ball and Youdell 2008); the channelling of power through performativity (Ball 2003b) and the development of (increasingly global) networks (Ball 2012).This special issue of the London Review of Education gathers six papers reflecting on the contribution of Stephen Ball to educational research, policy and practice. There are many ways of looking at this and the specific approach chosen here is to look at how his ideas travel (in the broadest sense) and to explore the ways in which they are used and recontextualised. This task informed the successive versions of the papers which were enriched by the comments from our anonymous reviewers.A key common reflection from the papers is that the contribution of Stephen Ball's research to the exchange of ideas is driven by a capacity to cross many boundaries. First of all, the papers show how his research incites dialogues between and across disciplines, theories and methods. The combination of the approaches of Foucault and Bourdieu (Ball 2013) and the use of the policy cycle do not only contribute to methodological and theoretical developments in the sociology of education and policy sociology but are also widely used by wider communities interested in exploring education policy. Another cross-boundary aspect which became apparent in this special issue relates to the dynamics between research, policy and practice. For example, the papers highlight many occurrences when Stephen Ball's research led some teachers and other education professionals to recontextualise the way they experienced policy and, as a result, to reflect on their practice (Ball and Olmedo 2013). This sense of empowerment is made all the stronger when his research invites us to reflect on policy and practice rath...