To date, there are no established scales to assess PrEP stigma among youth. We validated the Youth PrEP Stigma Scale within the Adolescent Trials Network P3 study (2019-2021). Data from sexual and gender minority youth (16-24 years) who were prescribed PrEP across nine domestic sites were evaluated (N = 235). Descriptive statistics, exploratory factor analysis, and correlation coefficients are reported. Results yielded a three-factor solution (PrEP Disapproval by Others, Enacted PrEP Stigma, and PrEP User Stereotypes) with strong factor loadings and Cronbach's alphas ranging from 0.83 to 0.90, suggesting excellent internal consistency. Correlations between this Scale, anticipated HIV stigma, perceived HIV risk, and disclosure of sexual identity were significant, indicating potential for robust application. Given the persistence of HIV infections among youth, stigma as a barrier to prevention, and expansion of PrEP modalities, the Youth PrEP Stigma Scale could enhance intervention and mechanistic research among youth at elevated risk for HIV acquisition.