Irregular migration is a complex global phenomenon. Ireland, like all other countries, is challenged to respond in an effective and humane manner. There are an estimated 30,000 undocumented migrants living in Ireland. Undocumented migrants, including children, are at greater risk of exploitation, poverty and social exclusion, and often live in situations of destitution. Ireland can no longer afford to ignore this situation. A broad package of measures to address irregular migration is required. Internationally, regularisation of undocumented workers is recognised as a necessary part of a workable solution to irregular migration. This briefing paper sets out some of the key factors underpinning the rationale for a regularisation programme in Ireland.