Since the 1970s, historiography about the pre-World War II phase of the Croatian Ustaša concentrated on Italian and Hungarian state support for Ante Pavelić's national-separatist/terrorist organization from approximately 1929–1934, and identified Nazi support when it became more significant in the late 1930s and put the group in charge of the Independent State of Croatia in 1941. More recent scholarship has investigated the support of Croatian exiles in the United States and Argentina for the Ustaša movement, as well as how the Ustaša regime, once in power, tried to legitimate its policies of racial “cleansing” and social revolution against capitalism and secularism. The first aim of this article is to return to the early period of the Ustaša, when it was a terrorist organization, and to show that it had an important base in Austria that senior Austrian police officials tolerated. The article, therefore, takes a somewhat different position from that of historian Arnold Suppan, who argued that the Austrian police could find no evidence that the Ustaša in Austria had been involved in terrorism, and that the Austrian government had made a good faith effort to expel Ustaša members. The fact that elements of the Austrian police indeed knew about the Ustaša network and protected certain senior members supports historian Gerhard Jagschitz's argument that the Vienna police had not turned over a new leaf in the postwar period and had not shed all political activities. However, Jagschitz concentrated on the problems surrounding the establishment of a domestic intelligence agency in the 1920s, showing how it ultimately was not effective. This article concentrates on 1929–1934, demonstrating that while the Austrian political police was not all-knowing, certain decisions not to share what it knew about ultra-nationalist Croatian terrorism damaged the Austrian police's international reputation. Second, this article argues that the Yugoslav police possibly turned to shadowy extra-judicial groups to carry out assassinations against Ustaša figures, in part because the Austrian police were not aggressive enough in repressing the organization. This adds an additional factor to the interpretations of historians James Sadkovich and Mario Jareb, who contend that Yugoslav police violence was an extension of the Serbian dictatorship's attempt to repress Croatian nationalism by any means necessary.