‘Laboratories of Terror’ explores the final chapter of Stalin’s Great Terror in Soviet Ukraine. When the Communist Party Central Committee and the Council of People’s Commissars of the USSR halted mass operations in repression in November 1938, large numbers of mainly Communist purge victims whose cases remained incomplete were released. At the same time, hundreds of NKVD operatives who had carried out the Great Terror were scapegoated and arrested. Drawing onmaterials from the largely closed archives of the Soviet security police, this collection of essays by an international team of researchers illuminates the previously opaque world of the NKVD perpetrator. It uncovers the mechanics and logistics of the terror at the local level by examining the criminalfiles of a series of mid-level NKVD operatives from across Ukraine. The result offers new perspectives on both Stalin’s central role in the architecture of the terror and NKVD perpetrators’ agency in implementing one of the most horrific episodes of twentieth-century mass violence.