Electoral systems have an impact on parties and voters’ ideology as well as government policies. Iversen and Soskice (2006) showed that governments elected under proportional representation favour wealth redistribution policies, a connection that Döring and Manow (2017) attributed to the strategic behaviour of the middle class and the inefficient geographic distribution of left-wing voters. However, these two do not exhaust all the possible mechanisms that connect electoral systems to governments’ ideological orientation. In this paper, we argue that left-wing parties maximize votes, policies and offices under proportional representation, particularly when the mean average district is high, and its variance is small. To test these ideas, we introduce measures of alternative explanations such as malapportionment and differential voter mobilization across districts, as well as an explicit measure of voters’ ideology as a control. We rely on a database that combines data from different comparative sources and our own malapportionment measures, including elections from consolidated democracies since 1945.