Objectives. Racial identity invalidation, others’ denial of an individual’s racial identity, is a salient racial stressor with harmful effects on the mental health and well-being of Multiracial individuals. The purpose of this study was to create a psychometrically sound measure to assess racial identity invalidation for use with Multiracial individuals (N = 497). Methods. The present sample was mostly female (75%) with a mean age of 26.52 years (SD = 9.60). The most common racial backgrounds represented were Asian/White (33.4%) and Black/White (23.7%). Participants completed several online measures via Qualtrics. Results. Exploratory factor analyses revealed three Racial Identity Invalidation factors: Behavior Invalidation, Phenotype Invalidation, and Identity Incongruent Discrimination. A confirmatory factor analysis provided support for the initial factor structure. Alternative model testing indicated that the bifactor model was superior to the three-factor model. Thus, a total score and/or three subscale scores can be used when administering this instrument. Support was found for the reliability and validity of the total scale and subscales. In line with the Minority Stress theory, challenges with racial identity mediated relationships between racial identity invalidation and mental health and well-being outcomes. Conclusions. Our findings highlight the different dimensions of racial identity invalidation and indicate their negative associations with connectedness and psychological well-being