Do voters see democracy entirely as a game of self-interest in which one person’s gain is another’s loss, or do they also view it as a search for the common good, as some democracy theorists have long conjectured? Existing empirical research that assumes entirely private interests cannot answer this question, by design. We develop an empirical model in which voters derive utility from both common-good and private considerations, and show formally how to disentangle the two preference components. We estimate the model on California ballot propositions from 1986 to 2020, and find that 46 to 87 percent of voters place significant weight on the common-good aspects of proposals. Common-good concerns mitigate the effects of voter polarization, which we find substantially increased over out study period – particularly in the last six years.