The Global Imaging Genetics of Adolescents initiative is a collaboration between several major cohorts in UK, Europe, USA, China, and India who investigate health outcomes in children and adolescents via behavioral and imaging genetic studies. Its aim is to enable comparative research on brain development and behaviour in different cultures, environments and ethnic groups, both in industrialised nations and low and medium income countries (LMIC). To this end GIGA is working towards harmonised data acquisition, retrieval and analysis.