This essay focuses on the problems of colonial security and modern colonial policing in the Netherlands-Indies, in the context of colonial state formation. It analyses the intent of police reforms implemented predominantly in Java, 1911–1919, and the results of those measures for the actual practice of modern colonial policing in the city of Surabaya. The Dutch colonial reformers intended to “modernize” the largely indigenous police force, making it both more efficient for state control and, ideally, more responsive to the citizenry’s need for security. The author's examination of three case studies involving the Surabaya police reveals the inherent problem—and the dilemmas of colonial policing—that hobbled this effort to ensure state control and improve security in a rapidly changing, ethnically divided city governed by a colonial regime.