Formation and functioning of single-party governments under the conditions of proportional voting system

The text deals with the formation and functioning of single-party majority and minority governments in democracies with proportional voting systems. It focuses on the conditions and circumstances of formation of such governments and on the aspects of political system which affect these processes - specifically on party systems that use the Sartori´s typology, on particular settings and effects of voting systems and on legal and customary rules of government formation, especially considering the relations between the government and parliament. Subsequent case studies are dedicated to particular instances of single-party governments in European Union countries (Spain, Portugal, Slovakia and Sweden) in the 21st century and to the circumstances of their formation. It is concluded that majority single-party governments are formed under the conditions of regular proportional voting system in moderate pluralism in the case of voters being inclined in a certain direction. The magnitude of constituencies is significantly influential in these cases. Minority single-party governments are formed in political cultures where it is acceptable, when no party wins an absolute majority of parliament seats, and if - thanks to the party system or to the rules (like negative parliamentarism or constructive vote of no confidence) and customs of government formation and dissolution - there is no possibility or need of forming a coalition government.