The environments that surround children shape their health for life. This City Health Talk brings together three perspectives on building healthier childhoods: Nesta's case for stronger regulation of food retail and advertising, Campinas's cross-sector approach that reaches over 14,000 people, and a voucher scheme for fruits and vegetables that supports families and market traders in South London. Together, they explore how national policy and local action can reshape the streets, schools and homes where children grow up.