The paper presents the Slovene and Croat concept of triadism in the years preceding the First World War. The author answers the question as to how a demanded third - Southern Slavic - state unit would look according to the Slovene and Croat politicians of the time, in the event of the Habsburg Empire being reconstructed in a triadist sense. He concludes that the idea of a Greater Croatian state unit had the widest support among the triadist plans. Such a state unit would be strongly Catholic in character and integrated on the principle of 'centralized federalism' as applied in the Greater Austria.