This thesis is concerned with the overrepresentation of black and minority ethnic (BME) children and looked after children, in the youth justice system in general and the secure state in particular, in England and Wales. In the period 1993 to 2008, youth justice was characterised by a process of extensive penal expansion. Since 2008, however, the child prison population has fallen dramatically. The decline has been linked to pragmatic cost reduction as well as an increase in diversionary measures which keep children out of the system altogether. However, BME children and looked after children have not benefited from this decline to the same extent as white children and non-looked after children. The contraction in the system has served to intensify existing inequalities. This thesis interrogates the nature and extent of the overrepresentation of these groups. It employs a mixed-methods approach which involves analyses of secondary data and in-depth interviews with 27 national youth justice and children's services professionals. This thesis builds upon and extends previous research, it determines that BME children are criminalised through 'institutional racialisation' which operates on micro, meso and macro levels. The thesis signals policing as having a particularly powerful influence on the levels of BME children in the system. The weight of these findings lie precisely in the fact that they are so longstanding. The thesis highlights that the precise nature and extent of the overrepresentation of looked after children is less clear as a result of insufficient official data. It determines that looked after children are disadvantaged in myriad ways, but that individualised explanations alone cannot account for overrepresentation. Principally, this thesis draws attention to failings in the care system which both increase the risk of youth justice contact and influence trajectories through the youth justice system. The research also considers the intersections between ethnicity, looked after status and youth justice involvement. It establishes that BME looked after children experience compounded disadvantage in the youth justice system. The thesis concludes that the broader landscape of economic austerity and crises within the youth justice system make it even more imperative that such injustices are acknowledged and addressed.