The purpose of this paper is to investigate the relationship between psychological traits and voting behavior. Investigated is the thesis that psychological traits are useful concepts for political scientists as predictors of consistency in behavior. Contending that previous trait theory research has been generally unimpressive, the author hypothesizes that traits may be specific to individuals as well as situations. This reform of trait theory is applied to six politically relevant traits: tendermindedness, radicalism-conservatism, F-scale, social desirability, locus of control, and machiavellianism. The criterion variables include 18 measures of electoral and non-electoral participation, ideology and partisanship, including: votes in campus, local, state and national elections, anti-war activity, party identification, political discussions, and attempts to persuade others. Findings indicate that segregating the sample into trait-relevant and trait non-relevant groups is meaningful since predictive power is distinctly enhanced in the trait-relevant groups. In addition, the analysis shows that the 18 criterion items cluster according to trait-predictability in highly interpretable ways. References relating to personality types, psychological studies, and political participation are included. (Author/DB)