An interdisciplinary team of researchers reports on how social norms — ‘patterns of behaviors or values that depend on expectations about what others do and/or think should be done’ — can be harnessed to bring about collective climate action and policy change.An interdisciplinary team of researchers reports on how social norms — ‘patterns of behaviors or values that depend on expectations about what others do and/or think should be done’ — can be harnessed to bring about collective climate action and policy change.