The central line of argument and analysis within this chapter is that penal expansion is derived from a politics of intolerance and punitiveness that has come to frame contemporary youth justice policy in England and Wales. In 2005, research detected an emerging consensus that the current number of children within penal institutions needed to be addressed as a matter of urgency. It is suggested that conditions may be emerging within which tolerance, penological rationality, and responsible concern might impact more positively upon youth justice policy and practice in coming years. Mapping the historical trajectory of youth justice policy and practice in England and Wales exposes a conspicuous similarity with custodial institutions. From the early 1990s to the present time a new punitiveness has consolidated within the youth justice system in England and Wales, illustrated by a sharp rise in the numbers of child prisoners. This chapter engages with the contemporary politics of penal custody derived from what past research has termed institutionalized intolerance. It argues that developments in law and policy, serving to detain increasing numbers of children in custodial institutions, negate a wealth of research evidence and practice experience, illuminating the counter-productive outcomes of penal custody. References