Collaborative network for adolescent nutrition and health in sub-Saharan Africa and India Our proposed project will focus on the nutrition and health of adolescent boys and girls. Adolescence is the stage of life, from 10 to 19 years of age, when children transition into adults. It is characterized by rapid growth, sexual maturation, widespread 're-wiring' and re-organisation of the brain, and an increase in the scope and complexity of social interactions. We currently have the largest generation of 10 to 19 year olds in human history, more than 1 billion worldwide, and half of these grow up in countries characterised by high levels of poor quality nutrition and rising rates of non-communicable disease (NCDs: obesity, heart disease and diabetes). In sub-Saharan Africa and South Asia, adolescents form 20-35% of the population.  It has recently become clear that adolescence is a critical phase in life for achieving human potential, and during which the physical, psychological, behavioural, social and economic foundations of adult health are consolidated. The recent Lancet commission on adolescent health points out that investment in this stage of the lifecourse has the potential to produce a 'triple dividend' benefiting adolescents now, into their future adult life, and into the lives of their children. Half of the inequality in the value of lifetime earnings is due to factors determined before the end of adolescence. Despite its significance, adolescence has been largely neglected in health and social policy terms; a phenomenon recognised by the recent UN Global strategy for women's, children's and adolescents' health. Adolescent nutrition has, in particular, been under-researched, leading to large knowledge gaps. There have been no comprehensive studies of nutritional status and physical activity across different populations and settings. Little is known about how nutrition and physical activity change through adolescence, what determines these changes, and how they influence growth, current health, future disease risk, and the health of the next generation. We do not understand the drivers of dietary and activity behaviours among adolescents, and how these could be changed to benefit health. Our application brings together a multi-disciplinary network of researchers interested in adolescent health from the UK, India and different regions of sub-Saharan Africa, with the collective expertise to carry out large-scale nutrition research. Our long-term vision is to 1) conduct in-depth studies of the dietary behaviour, nutritional status, body composition and physical activity of adolescents in vulnerable populations in these countries, and how these change through adolescence; 2) to understand, through qualitative research, the factors which determine their diet and activity behaviour at each stage of adolescence; and 3) develop and test context-specific interventions to improve adolescent health through nutrition.  In preparation for this ambitious future work, the current pump-priming application is to 1) consolidate the new network by holding two workshops, one in India, one in Africa; 2) conduct training in qualitative research methods and carry out pilot qualitative data collection to explore influences on dietary and activity behaviour in adolescents across multiple settings; 3) carry out literature reviews of existing data on the nutritional status of adolescents and existing policies for adolescent nutrition in the countries represented; 4) carry out secondary analyses using data from existing cohorts within the group, to examine how nutrition in young adolescence relates to adolescent growth and adult NCD risk markers; and 5) work together to develop the design of the future project, and prepare a larger grant application in 2018. A major objective of both the pump-priming work and the future larger study is to build capacity among early-and mid-career researchers in these countries for rigorous and cutting-edge nutrition research. The Global Challenges Research Fund (GCRF) supports cutting-edge research to address challenges faced by developing countries. The fund addresses the UN sustainable development goals. It aims to maximise the impact of research and innovation to improve lives and opportunity in the developing world.