This article explores the use of sanction as a technique to secure the engagement of individuals with intensive support and rehabilitation programmes. Sanction and enforcement became increasingly prominent under the New Labour governments, within rhetoric and rationalities of ‘non-negotiable support’, ‘gripping’ and ‘challenging’ families and ‘making them’ engage. The linking of support to financial penalty or other legal enforcement action for non-compliance was a defining element of Parenting Orders and Family Intervention Projects. The new coalition government’s ‘rehabilitation revolution’ is committed to retaining an emphasis upon early intervention, whole family approaches and parenting skills, with a (modified) continuation of enforcement action for non-engagement with support. This article explores the rhetoric, definitions and existing research evidence about the use of sanction in intensive intervention projects. It then presents evidence from recent evaluations of the Intensive Intervention Project programme and Housing Benefit Sanction pilots in England to identify the actual practices of sanction. The article concludes that ‘non-negotiable’ support is a fallacy; that sanctions and enforcement action are very limited in both their use and impacts; and that this has important implications for the new government’s rehabilitation agenda.