The literature on party competition structure in eastern Europe varies between aggregated large-N studies that propose uniform patterns of party competition across the region on the one hand, and disaggregated, case-focused studies identifying a plurality of country-specific patterns on the other. This article finds that both suffer from theoretical weaknesses. The aggregated works, arguing for common unidimensionality of party competition in the region, overlook significant cross-national differences, while the case-focused works, suggesting country-specific multidimensionality, do not identify commonalities. In effect, both sets of research fall short in explaining the variance of party competition in eastern Europe. This article consequently argues for the importance of bridging these findings of aggregate uniformity and idiosyncratic diversity through the use of refined theoretical explanations of party competition patterns in the region. To demonstrate the plausibility and utility of such an approach, the article builds a theoretical model of party competition in eastern Europe, and tests it by estimating the vote for left-wing parties across ten eastern European countries using the 2009 European Election Study.