From 2004 to 2016, The Atlantic Philanthropies together with government and other organisations invested in 52 programmes aimed at improving outcomes for children across the island of Ireland. These programmes used prevention and early intervention approaches in various areas of children’s lives, including learning, behaviour, health and development, parenting and inclusion. This investment was known as the Prevention and Early Intervention Initiative. This report explores the contribution of volunteers in evidenced informed services with families and children, and identifies some learning for policy makers and practitioners.