Have Americans' social attitudes become more polarized?

Many observers have asserted with little evidence that Americans' social opinions have become polarized. Using General Social Survey and National Election Survey social attitude items that have been repeated regularly over 20 years, the authors ask (1) Have Americans' opinions become more dispersed (higher variance)? (2) Have distributions become flatter or more bimodal (declining kurtosis)? (3) Have opinions become more ideologically constrained within and across opinion domains? (4) Have paired social groups become more different in their opinions? The authors find little evidence of polarization over the past two decades, with attitudes toward abortion and opinion differences between Republican and Democratic party identifiers the exceptional cases.