This paper draws on Keck and Sikkink's (1998) policy impact framework to analyse the role of evidence and ideas in the policy process through the lens of an international policy research project on childhood poverty, Young Lives. The paper begins by providing a brief overview of Keck and Sikkink's (1998) policy impact framework. This framework takes into account different stages in the policy cycle, from framing debates and agenda setting, to securing discursive and procedural changes from key policy actors, through to affecting policy and changing behaviour among target actors. The second section applies this fivefold framework to evaluate Young Lives' efforts to mainstream children in poverty policy debates. Given that the four participating Young Lives countries (Ethiopia, India (Andhra Pradesh), Peru and Vietnam) are geographically, politically, socio-culturally and developmentally diverse, we seek to tease out broader lessons for advocacy around children's rights. The conclusion in Section 3 reflects on the particular challenges and insights that child-focused advocacy work raises for international debates on evidence-based policy-making.