In the last 30 years, there was a rise in the political gender gap. The Center for the American Woman and Politics data shows that a larger proportion of women than men vote for the Democratic Party. Women tend to differ from men in several political issues endorsing more welfare policies and progressive policy changes and are less racist than men. Social dominance orientation (SDO) has been theorized to account for political gender differences. Men have higher average levels of SDO than women, everything else being equal. To test the gender invariance hypothesis, we believe it’s important to take into consideration people who not only identify with groups that hold specific hierarchy-enhancing or hierarchy-attenuating ideologies but who participate in them promoting their values and ideas. In this chapter, we describe the findings of research on gender differences in SDO of activists in political parties that range from extreme left-wing to extreme right-wing.