The Finnish electoral system combines open-list proportional representation (OLPR) and mandatory preferential voting. OLPR provides the Finnish electoral system with a high degree of intra- and interparty competition. The inherent duality of the system has a multitude of effects on how elections are played out at different levels. The chapter provides a thorough presentation of the basic features of the electoral system and discusses its consequences, with a specific focus on how the two levels of competition influence the internal logic of Finnish politics in terms of nomination of candidates, how campaigns are fought, elections won, and the behavior and attitudes of voters, politicians, and parties.