881 European Journal of Political Research 44: 881–898, 2005 Are moderate parties rewarded in multiparty systems? A pooled analysis of Western European elections, 1984–1998 LAWRENCE EZROW University of California, Santa Barbara, USA and VU Amsterdam, The Netherlands Abstract. We present cross-national analyses – both cross-sectional and longitudinal – esti- mating the vote shares for approximately 80 parties across Western Europe from 1984 to 1998. The results indicate that parties’ vote shares increase with their proximity to the centre of the voter distribution, although the effects are relatively small. These findings corrobo- rate the theoretical results reported by Lin et al. in their article ‘Equilibrium in Multican- didate Probabilistic Spatial Voting’ (Public Choice,Vol. 98, pp. 59–82), and provide support for conclusions reported by other authors who rely on simulations of individual-level data from national election surveys. Introduction Can parties in Western Europe gain votes by converging towards the mean (or median) voter’s position? Traditional spatial theory clearly predicts that, ceterus paribus, parties contesting two-party elections gain votes by converg- ing towards the centre (Downs 1957). However, prior studies of models of multiparty elections report conflicting conclusions. Theoretical models that assume deterministic policy voting suggest that noncentrist positioning may be optimal 1 (Cox 1990; see also Adams 2001), while models with probabilistic voting suggest that parties increase their expected votes by shifting in the direction of the mean voter position (Lin et al. 1999; De Palma et al. 1990). However, recent work by Norman Schofield (2004; see also Schofield & Sened forthcoming) and by Adams and Merrill (1999, 2000; see also Adams 2001; Merrill & Adams 2002) has challenged this conclusion, suggesting that when measured nonpolicy-related voting influences are introduced into the proba- bilistic voting model, then parties may enhance their vote by shifting away from the centre of the voter distribution. 2 In addition, simulations based on individual-level survey data from real- world elections also reach conflicting conclusions, with some studies finding that centrist positioning would increase support for parties contesting multi- party elections (Alvarez et al. 2000a, 2000b; Schofield et al. 1998a, 1998b), while other simulation studies conclude that parties may maximize votes by © European Consortium for Political Research 2005 Published by Blackwell Publishing Ltd., 9600 Garsington Road, Oxford, OX4 2DQ, UK and 350 Main Street, Malden, MA 02148, USA