Neurodiversity refers to the idea that all brains--no matter their differences--are valuable and should be accepted. Attitudes toward the neurodiversity perspective can have real-life impacts on the lives of neurodivergent people, from effects on daily interactions to how professionals deliver services for neurodivergent individuals. In order to identify negative attitudes toward neurodiversity and potentially intervene to improve them, we first need to measure these attitudes. This article describes the development and initial validation of the Neurodiversity Attitudes Questionnaire (NDAQ), including item revision based on expert review, cognitive interviews, systematic evaluation of participants' response process, and analysis of the instrument's internal factor structure using exploratory structural equation modeling. Pilot analysis with 351 individuals mostly living in the United States who were currently working in or intending to pursue helping professions indicates that the NDAQ has construct validity, is well understood by participants, and fits a five-factor structure. While the NDAQ represents the first instrument designed to specifically assess attitudes toward the neurodiversity perspective, further validation work is still needed.