While coalition agreements are significant in structuring government behaviour, their comprehensiveness varies considerably across cabinets. We argue that the average correspondence between parties' priorities and portfolio allocation is important in explaining the comprehensiveness of coalition agreements because coalition parties that have obtained their preferred portfolios have less incentive to negotiate a detailed coalition agreement. We test our argument by combining newly collected data on coalition agreements drafted by 218 cabinets in 24 Western and Eastern European countries from 1945 to 2014 with data on the distribution of ministerial portfolios. We find that the shorter and less comprehensive the agreements, the higher the correspondence between parties' priorities and portfolio allocation. Our results have important implications for our understanding of coalition governments and the relationship between government formation and cabinet governance.