This article assesses party effects on the performance of public services. A policy-seeking model, hypothesizing that left and right party control affects performance, and an instrumental model, where all parties strive to raise performance, are presented. The framework also suggests a mixed model in which party effects are contingent on party competition, with parties raising performance as increasing party competition places their control of government at increasing risk. These models are tested against panel data on English local governments’ party control and public service performance. The results question the traditional account of left and right parties, showing a positive relationship between right-wing party control and performance that is contingent on a sufficiently high level of party competition. The findings suggest left–right models should be reframed for the contemporary context.