This article examines alternative visions of “strong” party systems by analyzing relationships between party systems and several dimensions of performance of the political process in 28 democracies of the 1967-1976 decade. Party system theorists agree that voting support for extremist parties manifests a weakness in the party system. They disagree, however, about the virtues or vices of party majorities and close linkages between social groups and parties. The evidence, including multivariate analysis of party system types and characteristics, with controls for environmental conditions, indicates that during this period extremist party support was associated with executive instability and mass rioting. Scholarly concern about other aspects of party system strength or weakness should focus on the desired feature of political performance. The representational, multiparty systems were most successful in limiting rioting. Aggregative majorities, responsible majorities, and representational party systems all had good executive stability in the short run, although the first two types seemed somewhat more stable over the decade. Aggregative majority party systems were associated with low citizen voting participation.