This paper contributes to our growing understanding of the processes underpinning contrasting rates of school exclusions both within and across the different jurisdictions of the UK. Wales is often compared favourably to its larger neighbour England, where rates of permanent exclusions have risen dramatically in recent years. One explanation for Wales' lower rates might lie in the very different values which underpin its education policies. However, the prevailing policy discourse can only be part of the explanation and cannot account for the high levels of variation in rates of 'official' school exclusions across Wales, nor the many forms of 'hidden' exclusion going on in Welsh schools. Drawing on interview data with policy-makers and practitioners, this paper points to the need to explore how policy is enacted at the local level. This entails taking into account the often unacknowledged conditions in which schools operate and the unintended consequences of policy imperatives which can lead to outcomes that frustrate and undermine anti-exclusionary practices and processes.