Young Lives is the first multi-disciplinary longitudinal study of childhood poverty to be carried out in more than one developing country. Drawing on the practical experiences of our research teams, this Methods Guide aims to document and share some of the lessons we have learned along the way. It provides an overview of how the Young Lives research has been carried out. It gives readers an insight into the diverse methods and processes that are used to carry out a complex longitudinal study made up of many different components. It offers lessons on building and managing research partnerships, designing and carrying out multidisciplinary research, managing and analysing data, and using research to influence policy. Written in 2011, the Methods Guide reflects on a decade of experience and iterative change.