Multiparty government has often been associated with poor economic policy-making, with distortions like lower growth rates and high budget deficits. One proposed reason for such distortions is that coalition governments face more severe 'common pool problems' since parties use their control over specific ministries to advance their specific spending priorities rather than practice budgetary discipline. We suggest that this view of multiparty government is incomplete and that we need to take into account that coalitions may have established certain control mechanisms to deal with such problems. One such mechanism is the drafting of a coalition agreement. Our results, when focusing on the spending behavior of cabinets formed in 17 Western European countries (1970-1998), support our claim that coalition agreements matter for the performance of multiparty cabinets in economic policy-making. More specifically, we find clear support for an original conditional hypothesis suggesting that coalition agreements significantly reduce the negative effect of government fragmentation on government spending in those institutional contexts where prime ministerial power is low.