This book is about the opportunities and challenges involved in mainstreaming knowledge about children in international development policy and practice. It focuses on the ideas, networks and institutions that shape the development of evidence about child poverty and wellbeing, and the use of such evidence in development policy debates. It also pays particular attention to the importance of power relations in influencing the extent to which children's voices are heard and acted upon by international development actors. The book weaves together theory, mixed method approaches and case studies spanning a number of policy sectors and diverse developing country contexts in Africa, Asia and Latin America. It therefore provides a useful introduction for students and development professionals who are new to debates on children, knowledge and development, whilst at the same time offering scholars in the field new methodological and empirical insights.