Objectives: Nonsuicidal self-injury is a behavior typically used to regulate emotions, resulting in damage to one’s body without suicidal intent. Self-injury may indicate a need for psychological support, yet stigma is a major barrier to disclosure for many. Despite stigma’s potential impact on help-seeking, recovery, and wellbeing, our understanding of self-injury stigma is limited. While traction is building in this space, few measures of self-injury stigma exist to allow exploration of its impacts. In this study, we outline the preliminary validation of the Self-Injury Stigma Questionnaire (SIS-Q), which was developed to capture the features of self-injury stigma conceptualised in the NSSI Stigma Framework (Staniland et al., 2021). Method: First, we developed item pools representing five stigma perspectives: Public, Personal, Internalized, Anticipated, and Enacted, and reflecting six dimensions of stigma: Origin, Concealability, Aesthetics, Course, Peril, and Disruptiveness. These items were piloted with a sample of 316 ( M age = 32.1, 68% male, 40% with a history of self-injury) participants. Following item reduction, the scales were administered to 722 ( M age = 29.2, 27.3% male, 55.7% with a history of self-injury) participants, and data were analysed for validity, reliability, and invariance. Results: Confirmatory factor analyses revealed four factors: Origin, Concealability, Peril, and Disruption. Internal consistency, convergent and divergent validity, and measurement invariance were demonstrated. Conclusion: The SIS-Q offers a comprehensive and theoretically informed measure to support ongoing efforts investigating the development and persistence of self-injury stigma, and the impact it has on individuals with lived experience of self-injury.