Recent guidelines on the measurement of gender in surveys recommend a two-step strategy that asks about sex assigned at birth followed by current gender identity using a small number of offered response categories (e.g., female, male, transgender) and an open response field to capture any residual categories (“not listed, please tell us”). However, more research on several fronts is needed to continue to refine our measurement strategies across contexts, and this work continues to be critically important with the dismantling of federally funded research regarding gender identity. In the current study, we examine the impact of response format on the measurement of gender identity. This study reports results from a between-subjects experiment embedded in a campus climate survey about inclusion and belonging at a large Midwestern university in Fall 2024. Over 16,000 students were asked, “What is your gender?” and subsequently randomly assigned to respond using one of two response formats. The first allowed respondents to “select-one” of the response options “woman, man, nonbinary, not listed (please tell us),” and was followed by the question “Are you transgender? Yes/No.” The second included the response options “woman, man, nonbinary, transgender, not listed (please tell us)” and instructed respondents to “select all that apply.” We examine the distribution of responses, item nonresponse, the number of gender categories reported, response times, and concurrent validity (in terms of the association between gender and survey outcomes about campus climate) across the two formats. While the results mainly show similarities in outcomes between the response formats, respondents are more likely to indicate they are transgender in the “select-one” format. By contrast, respondents are more likely to indicate gender expansiveness other than “transgender” or “nonbinary” with the “select-all” format. We discuss the implications of these findings for future research.