This paper presents a new measure of the real national income of the Soviet Union on the eve of World Mar II and during the war years. The new measure is compared with existing official and independent estimates. The heavy weight of the wartime Soviet defence burden is confirmed by the standards both of peace time and of other powers engaged in World War II. The Soviet commitment of labour resources to the war was also very heavy, but does not seem so impressive by international wartime standards. This reflects, in part, a real underlying constraint on Soviet wartime mobilisation rooted in the labour requirements of a large, low productivity agricultural sector.