Criminalizing the Casbahs explores how French police officers in Marseille and Algiers associated the spaces they saw as North African—the "Casbahs"—with a particular form of criminality, one they insisted was inherently North African. Through local but connected histories of policing in these two cities, Danielle Beaujon traces how police practices mapped the racialization of North African colonial subjects onto urban space. By demarcating and racializing space, the French police created repressive methods for controlling North African bodies while proclaiming to uphold republican ideals of colorblind justice. The invasive, often violent, policing of North Africans in the French Mediterranean blurred the political and the personal, broadening the spectrum of police power with lasting consequences for post-colonial policing. Criminalizing the Casbahs shows how patterns of discrimination created in the daily interactions between police officers and North Africans continue to resonate in debates about police accountability in France today.