Our knowledge on the personality basis of ideological attitudes and prejudice, while based on a substantial body of research, suffers from a potentially serious methodological limitation: an overreliance on the method of self-reports. Across 2 studies (Ns = 193, 424), we examined associations between the Big Five personality dimensions, Right-Wing Authoritarianism (RWA), Social Dominance Orientation (SDO), and generalized prejudice, using both self-report and peer-report data stemming from 1 (Study 1) or 2 (Study 2) peer rater/s. Correlational and regression analyses as well as structural equation modeling showed that (a) the associations between personality dimensions, ideological attitudes, and prejudice were largely similar to previous research for both data sources; (b) RWA and prejudice showed a similar level of self-peer agreement to personality dimensions; (c) most of the known associations between personality, ideological attitudes, and prejudice were replicated also when measured by independent methods; (d) peer reports had some incremental validity in predicting ideological attitudes and prejudice; and (e) there was evidence that Openness to Experience and Agreeableness predicted prejudice directly and not only indirectly via RWA and SDO, respectively. Implications for the status of RWA, SDO, and prejudice as individual-difference constructs and for their bases in personality dimensions are discussed.