In 2000, the US Census Bureau acknowledged multiracial Americans on the decennial census in an attempt to better capture racial heterogeneity and to more closely align what is publicly collected on forms with people's personal understandings of their racial identity. In this article, we start a discussion of how the census—a major source of political identity recognition and legitimation—could be more inclusive of gender variance. We ask: (1) Is there support for a transgender category on the US census? (2) Who might select a transgender option if it were provided? To answer these questions, we conducted questionnaire research at three transgender and genderqueer conferences and found strong support for the inclusion of a transgender category. Conversely, we found that many people did not currently check “transgender” on forms when given the opportunity. As we show, the decision to check “transgender” varies by what we term gender identity validation. In other words, people who identified as male or female and who felt others viewed them as unequivocally male or female, respectively, were less likely to check “transgender” than people who identified as transgender or who experienced a discrepancy between their self-perceived and other-perceived gender identity. These differences suggest that—similar to the push for adding a multiracial category to the census—the expansion of sex/gender categories is most likely to come from individuals who experience themselves as constrained by the existing possibilities and/or who are stigmatized by others' conceptions of the appropriate alignment of bodies and genders.