Exposure to deprivation and distress in childhood can have profound and lasting consequences for children as they grow up, but the effects vary widely across individuals and contexts. How much do we understand about child development in these circumstances? It is often assumed that economic development will improve well-being, how have rapid socio-economic transformations impacted on children? And what kind of evidence do policymakers need in order to implement effective interventions that both harness economic growth and also deliver benefits for poor children?

Inequality of opportunity is ‘a universal challenge that the whole world must address’, the UN Secretary-General wrote recently in his synthesis report on the post-2015 agenda. Many of the disparities seen between individuals and social groups take hold during childhood, and as new findings from Young Lives show, too often opportunities close to the poorest children well before they become adults.

Rapid economic growth over recent years has seen millions of people around the world lifted out of poverty. But the distribution of growth has been hugely uneven; millions more have been left behind, unable to access the benefits of rising living standards and condemned to watch as others take advantage of improved job prospects and expanding infrastructure and services.

Inequalities combine in a range of ways to undermine the development of children’s full potential. Not having access to pre-school education, for example, contributes to the inequality of opportunity experienced by poorer children, while inequalities of risk mean they are more likely to experience illness in the family, and their family is less likely to have the financial resources to cope. Children’s experiences of inequality in themselves undermine their development, and can also affect their self-confidence, their relationships and their sense of well-being.

Improving children's life chances is central to development in low- and middle-income countries. Half the population of sub-Saharan Africa are aged 18 or younger, and young people comprise nearly half of all people living in extreme poverty worldwide. Poverty undermines not only children's rights to life, survival, and development, as enshrined in the UN Convention on the Rights of the Child, but also the skills and capabilities that fast-changing economies need for future growth.