In this lecture Professor Attanasio will talk about the recent interest in child development in developing countries, through intervention in early years, and will describe a pilot intervention programme that his research team has been developing in Colombia and India. Early years intervention has proved to be very effective in having long lasting impacts on individual development, and this lecture will discuss the challenges of identifying modalities that can be delivered at low cost and therefore scaled up in developing countries, and understanding the mechanisms through which these interventions work.