Objective. Societal inequality, including structural racism, impacts Black American young adults (e.g., Gómez, 2015). The context of racism further impacts those who experience violence (e.g., Brown, 2008). Cultural betrayal trauma theory (CBTT; e.g., Gómez, 2019) proposes (intra)cultural trust, such as solidarity in the Black community, is a protective factor against racism. As a violation of (intra)cultural trust, within-group violence is a cultural betrayal trauma. Though there is evidence in support of CBTT (e.g., Gómez & Gobin, 2020), an ongoing limitation of this work is that there are no validated measures of aspects of CBTT. The purpose of the current two-study report is to develop and validate the Cultural Betrayal Multidimensional Inventory for Black American Young Adults (CBMI-BAYA), with questionnaires for (intra)cultural trust, cultural betrayal, violence & discrimination, (intra)cultural pressure/support, and posttraumatic growth. Method: Following creating questionnaires based on the literature and incorporating content expert feedback, both studies administered the CBMI-BAYA and convergent/divergent validity measures to Black university students (Study 1; N = 342) and Black community young adults (Study 2; N = 619). Results. Across two studies, confirmatory factor analyses, correlational analyses, content expert feedback, and theoretical contribution review by the authors resulted in a validated, cultural congruent multidimensional inventory for assessing CBTT specifically and violence in the context of racism generally with Black American young adults. Conclusion. The CBMI-BAYA can engender research on violence, discrimination, and in-group dynamics with Black American young adults, which has implications for basic research that can inform culturally competent violence prevention and intervention programs.