Recent research suggests that children of prisoners are at risk for a range of adverse outcomes throughout their lives. However, there is almost no information about how many children prisoners have, where their children are or who looks after them. This article describes children's circumstances following their father's imprisonment, using a survey at an English prison. It is roughly estimated that 1 per cent of children under 18 experience parental imprisonment each year in England and Wales. It is argued that prisoners and their children are vulnerable to multiple types of social exclusion, including: pre-existing deprivation; loss of material and social capital following imprisonment; stigma; ‘linguistic exclusion’; political exclusion; poor future prospects; and administrative invisibility. Despite the apparent prevalence and urgency of the problem, the population of children of prisoners is unmonitored, under-researched and unsupported by the statutory sector. In the UK, failure to support children of prisoners reflects an era of punitive penal policy, and a lack of commitment to reduce social exclusion by the Government.