The aim of this study was to examine the learning effectiveness ( cognitive and affective) of the simulation game 'Communism, Fascism and the League investigates' developed by the writer for use in senior school (Years 11 and 12) Modern History. This was done by comparing the learning from the simulation gaming method with that from the traditional teaching method, employed by the same teacher ( the writer). A detailed unit of work, 'League of Nations 1919-1934, Russia 1917-1934 and Italy 1918-1934', was prepared for the traditional teaching method. An attitude test and an achievement test were developed to assess the specific cognitive and affective learning outcomes of these teaching methods. The attitude test was administered as a pretest to all participants. At the conclusion of teaching, the same attitude test was presented as a post-test and Repeated Measures MANOVA used to analyse the attitude data. The achievement test was also completed by all participants at the conclusion of the learning activities and student's t- tests were used to analyse the data from the achievement test and its sub- tests. The results of the research revealed that there was not statistically significant differences for total achievement between the traditional method and the simulation gaming method, but that when the total achievement test was divided into specific sub-tests for different cognitive behavioural levels, the simulation game was superior to the traditional method. The simulation gaming method was also more effective than the traditional teaching method for producing positive attitudes regarding the value of history, empathy with people of the past, and relationships between present day events and those of the past.