Why did the Soviet Union intervene in Hungary in 1956 but not in Poland? This article reviews the “historical thesis”, “personality thesis”, and “neutrality thesis”. It concludes that, while the new archival sources do not radically alter these three older theses, they do yield some insights. Wladyslaw Gomulka was perhaps less successful in deterring the Soviet leaders during the latter’s 19 October visit to Poland and less secure politically in his own country than originally thought. In addition, Imre Nagy may not have been as progressive, given his initial opposition to the very decisions for which he has gone down in history as having made.