The American film industry voluntarily classifies films, using the well-known MPAA ratings. The industry claims this is preferable and more liberal than the alternative approach of government classification. In Canada, film classification is mandatory in most jurisdictions, and performed by provincial governments. This thesis demonstrates that the Canadian government controlled mandatory ratings systems for films results in more liberal film ratings than the voluntary system in the United States, for most mainstream films. An analysis of one hundred recent releases and case studies support this conclusion. The histories and operations of the agencies in Canada and the United States, and differences among the provinces, are reviewed to identify factors leading to the different ratings, as well as challenges to the ratings systems. A key factor may be that Canadian agencies classify films not subject to MPAA classification.