This work is under a CC-BY license. You are free to copy and redistribute the material in any format, as well as remix, transform, and build upon the material as long as you give appropriate credit to the original creator, provide a link to the license, and indicate any changes made.Binary gender questions are often criticized for their inability to identify gender minorities (i.e. transgender and non-binary people) and their inconsistency with modern multidimensional theories of gender. Several inclusive gender questions have been proposed to address these problems, but the evidence supporting their use is less conclusive than many organizations have claimed, and the existing body of literature is generally lacking in theoretical grounding. This dissertation aims to partially address this gap between theory, measure development, and measure application. Chapter 1 explores previous conceptualizations of gender from a variety of disciplines and explains why the binary gender question is theoretically and pragmatically inadequate for assessing gender and transgender status, while Chapter 2 reviews existing literature proposing alternatives to the binary gender question. Chapters 3 through 5 provide novel empirical evidence from two studies about the simplicity, acceptability, and validity of the most-commonly recommended gender identity measures. Chapter 6 shifts focus from transgender participants to society at large, testing the hypothesis that some gender question formats may cue gender essentialism, and that revising them might thus reduce prejudice toward transgender people. Finally, Chapter 7 describes an attempt to extend transgender-inclusive questions to the context of sexual orientation, a construct which has historically been grounded in a binary view of gender.