The Lancet Series on Childhood Pneumonia and Diarrhoea, led by Aga Khan University, Pakistan, provides evidence for integrated control efforts for childhood pneumonia and diarrhoea.The series of four papers assesses the global burden of these two illnesses and identifies a set of highly cost-effective interventions that can prevent most diarrhoea deaths and nearly two thirds of pneumonia deaths by 2025, if delivered at scale. It also highlights the findings from consultations with several hundred frontline workers in high-burden countries and explores the barriers and enablers they face in dealing with these two diseases and potential ways forward. The final paper represents a call to action and discusses the global and country-level remedies needed to eliminate preventable deaths from these illnesses by 2025.