The official data on slums and basic urban services are important sources for Indian planners and policy makers. With regard to national and international benchmarks they are consulted in order to identify and target those in need of development schemes. This article takes a closer look at the official definitions and numbers and raises questions about their reliability and their comprehensiveness. By comparing these statistics with findings obtained during fieldwork undertaken between 2011 and 2014 in the southern Indian city of Hyderabad questions emerge concerning the effectiveness in helping the most marginalized sections of society.