A Case of a Surplus Majority Government: The Finnish Rainbow Coalition Ann-Cathrine Jungar* Surplus majority government is the most frequent type of cabinet in postwar Finland. The case study investigates the explicative power of two groups of theories of surplus majority government on the Finnish rainbow coalition formed in 1995. Firstly, theories that model surplus size as instrumental for government capability, i.e. surplus size as critical to decision- making capability. Secondly, theories that model the surplus size as a possibility or where the size is the result of the expected utility of government being higher than that of opposition for the political parties in terms of goal realisation. The main materials studied are internal party documentation and interviews with key people. The result of the study is that parties' strategic features best explain the surplus size of the rainbow coalition, since participation in government o¡ers greater opportunities for the realisation of party goals, such as policy, votes and future o¤ce. Introduction Why do all, or almost all, political parties take part in government? And, why does the formateur party include parties that are surplus from the point of view of controlling a su¤cient parliamentary majority? This article investigates the phenomenon of surplus majority government (SMG) by focusing on the Finnish rainbow government that was formed after the parliamentary elections in 1995 and re-formed after the parliamentary elections in 1999. 1 The purpose is to scrutinise the explanatory power of two di¡erent groups of theories of SMG in the Finnish case. Firstly, there are theories that model SMG as a necessity, i.e. as the only type of government that possesses governmental capability. Secondly, SMG can be conceived of as a possibility. Then SMGs form because the political parties derive more individual utility from taking part in and sharing power in oversized governments than they can from participating in smaller cabinets or remaining in opposition. SMG can be conceived of as a possibility or an opportunity. Scandinavian Political Studies, Vol. 25 ^ No. 1, 2002 ISSN 0080^6757 # Nordic Political Science Association * Ann-Cathrine Jungar, Department of Government, Uppsala University, Box 514, SE-751 20 Uppsala, Sweden. E-mail: ann-cathrine.jungar@statsvet.uu.se 57