In three studies across three cultures (U.S., Sweden, and Israel), we examine whether implicit theories about groups are associated with political identity and whether this relationship is mediated by Social Dominance Orientation (SDO). Study 1 found that raising the salience of entity beliefs leads to increased right-wing political self-identification on social issues, although no such effect was found regarding general or economic political identity. In Study 2, we found that the more participants endorsed entity beliefs about groups (vs. incremental beliefs about groups), the more they identified as political rightists (vs. leftists) in the U.S., Sweden, and Israel. SDO mediated this relationship in the U.S. and Swedish samples, but not in the Israeli sample – a political setting in which political identity is largely determined by attitudes regarding the Israeli-Palestinian conflict. Study 3 showed that SDO mediated the relationship between implicit theories about groups and Israelis’ political identity regarding social/economic issues, but did not have such a mediating role with respect to political identity regarding the Israeli-Palestinian conflict. Theoretical and practical implications are discussed.