The question of ‘colonial legacy’ has been the subject of heated debate within the social sciences in France since the mid-2000s. Disagreement centres on the question of how the colonial past acts upon post-colonial immigration in the present. Formulating an answer requires a fairly precise definition of colonial legacy. This chapter treats it as a set of symbolic resources and practices constructed under colonialism, notably categories of understanding, juridical logics and administrative practices, which are reactivated vis-à-vis post-colonial immigration. Reactivation does not imply an identical reproduction—rather, it is shaped by a new historical context, legal framework and the strategies of various actors. On that basis, this chapter uses a case-study approach to seek to understand how and why a reactivation took place in specific historical circumstances: those of the Minguettes district of Vénissieux, in the suburbs of Lyon, between the end of the 1960s and the early 1980s. The analysis focuses on the domains of housing policy and policing, during this period. In terms of housing, the idea of a ‘tolerance threshold’ underlay discriminatory practices by the Communist municipality and HLM operators which favoured forms of social and ethnic segregation, not just between estates but also between particular buildings. As for policing and ‘riot prevention’ strategies, the racialisation of social phenomena—particularly with regard to ethnic minority youths—fed into a consensus view of criminality that shaped policies towards these neighbourhoods. Overall, the chapter argues, both the management of social housing and policing strategies were profoundly influenced by colonial categories of understanding.