This article offers the first systematic investigation of the institution of opera censorship in Russia during the reign of Nicholas I. Drawing on new archival sources, it examines censorship legislation, the organisation of dramatic (i.e., theatre) censorship, the workings of its bureaucracy, censors’ reports and protocols and Nicholas's personal decrees on productions of specific operas, and printed and manuscript librettos. From these, it distils the patterns of state intervention in opera, revealing a remarkable fluidity – even capriciousness – of approaches. Decisions to ban or permit, and specific intrusions into the texts, were based on the censors’ adherence to or disregard for the Empire's censorship laws, Nicholas's inclinations and impulses, changes in cultural policy, practical needs of the Imperial Theatres, the shifting political climate at home and abroad, and, most of all, the national point of origin of the operatic work under review. In addition to surveying the trends, the article offers three case studies: Glinka's Zhizn’ za Tsarya (A Life for the Tsar), Verdi's Rigoletto and Meyerbeer's Les Huguenots.