Drawing on the practical experiences of our research teams, this Methods Guide aims to document and share some of the lessons we have learned in recent years. 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 designing and carrying out multidisciplinary research, managing and analysing data, and cohort maintainance such as attrition and tracking. This guide has been updated in 2017 as the Guide to Young Lives Research.