Economic interests, the influence of economic ideas and politics have been put forward in the literature as explanations for the British Repeal of the Corn Laws in 1846. In this paper, we will evaluate these competing explanations using the case of the liberalization of Belgian corn tariffs. The Belgian protectionist Corn Laws of 1834 were abolished in different steps between 1845 and 1873. The first part of this paper uses quantitative methods to assess the success of party affiliation, personal interests and the economic profile of the constituencies in predicting voting behavior. Thanks to the detailed censuses of 1846 on agriculture, industry and population, it is possible to typify the economic make-up of the electoral districts in much more detail than in the British case. However, the analysis of roll-call voting proves that party affiliation and personal and constituency economic interests are insufficient to explain the shift towards free trade. The second part of the paper then discusses the role played by political strategy and ideas in the liberalization of corn tariffs, using a qualitative analysis of the debates on tariff policy. The large number of votes over a forty year period allows us to document the relationship between ideas and interests in a new way.