Gender classifications often are controversial. These controversies typically focus on whether gender classifications align with facts about gender kind membership: Could someone really be nonbinary? Is Chris Mosier really a man? I think this is a bad approach. Consider the possibility of ontological oppression, which arises when social kinds operating in a context unjustly constrain the behaviors, concepts, or affect of certain groups. Gender kinds operating in dominant contexts, I argue, oppress trans and nonbinary persons in this way: they marginalize trans men and women, and exclude nonbinary persons. As a result, facts about membership in dominant gender kinds should not settle gender classification practices.