This Briefing Paper summarises ODI’s work on understanding how policy processes operate in the real world, as part of its mandate to inspire and inform policy and practice that lead to the reduction of poverty. ODI’s Research and Policy in Development programme (RAPID) helps other organisations, and ODI itself, lock together high quality applied research, practical policy advice, and policy-focused dissemination and debate. RAPID also ensures organisations have the skills, capacities and networks necessary to engage successfully in policy discussions. The paper condenses five years of work (see Box 1 overleaf) into six key lessons that are essential to any researcher or organisation wishing to generate evidence-based policy change, and an eight-step approach for policy entrepreneurs wishing to maximise the impact of research on policy. This is known as the RAPID Outcome Mapping Approach (ROMA).