In June 2008, the United Nations Secretary-General (SG) reaffirmed that ‘integration’ is the guiding policy for all conflict and post-conflict situations where the UN has a Country Team and a multi-dimensional peacekeeping operation or political mission/office (Secretary-General Decision No. 2008/24 (SG Decision 2008 – see Annex 1) Noting the concerns expressed by many in the humanitarian community, the SG Decision of 2008 also stated that integration arrangements ‘can yield significant benefits for humanitarian operations … should take full account of recognised humanitarian principles, allow for the protection of humanitarian space, and facilitate effective humanitarian coordination with all humanitarian actors’ (UN, 2008: para i (e)). Intense debate has, however, continued within both the UN system and the Inter-Agency Standing Committee (IASC) on whether UN integration supports or undermines humanitarian space.2 This debate has tended to focus on principled arguments rather than an analysis of empirical evidence. In order to address this, in its meeting of 12 March 2010 the UN Integration Steering Group (ISG) agreed on the need for an independent analytical study to assess the impact of UN integration arrangements on humanitarian space based on evidence collected at the country level.3 The decision was welcomed by the IASC and the various consortia of non-governmental organisations (NGOs). In January 2011, on behalf of the ISG, the Office for the Coordination of Humanitarian Affairs (OCHA), the Department of Political Affairs (DPA) and the Department for Peacekeeping Operations (DPKO) commissioned the Humanitarian Policy Group (HPG) at the Overseas Development Institute and the Stimson Center to jointly undertake this study, noting their research and policy expertise in the fields of humanitarian action and peacekeeping, respectively. The research team comprised HPG Research Fellows Victoria Metcalfe and Samir Elhawary, and Alison Giffen, Research Fellow at the Stimson Center.