Drawing on a range of sources, this article addresses the way in which various groups set about mapping the slums of Edwardian Norwich to bring understanding and order to the disordered world of the city's 750 courts and yards. It focuses on the social scientific investigations incorporated in the reports of the Medical Officer of Health: The evidence of social investigators; The findings of charitable bodies and the writings of local journalists, whether addressing the slum issue directly or reporting news stories set in slum areas. It shows how these individuals and groups identified, categorized and interpreted the slums and their dwellers and, by making the unknown known, encouraged a more vigorous intervention by the local state in the lives of the poor. It demonstrates the way in which these concerns and ideals came together in the moral panic which followed the Norwich Flood of August 1912, an event which revealed the dreadful state of the inner-city housing to a city-wide audience and culminated in the City's first public housing scheme. It shows how the imperus to demolish slums and build public housing on the outskirts of the city was conditioned by both the application of medical criteria and traditional moral constructions of the characters of slum dwellers.