Racial microaggressions are subtle statements and behaviors that unconsciously communicate denigrating messages to people of color. In recent years, a theoretical taxonomy and subsequent qualitative studies have introduced the types of microaggressions that people of color experience. In the present study, college- and Internet-based samples of African Americans, Latina/os, Asian Americans, and multiracial participants (N = 661) were used to develop and validate the Racial and Ethnic Microaggression Scale (REMS). In Study 1, an exploratory principal-components analyses (n = 443) yielded a 6-factor model: (a) Assumptions of Inferiority, (b) Second-Class Citizen and Assumptions of Criminality, (c) Microinvalidations, (d) Exoticization/Assumptions of Similarity, (e) Environmental Microaggressions, and (f) Workplace and School Microaggressions, with a Cronbach's alpha of 0.912 for the overall model and subscales ranging from 0.783 to 0.873. In Study 2, a confirmatory factor analysis (n = 218) supported the 6-factor model with a Cronbach's alpha of 0.892. Further analyses indicate that the REMS is a valid measure of racial microaggressions, as evidenced by high correlations with existing measures of racism and participants' feedback. Future research directions and implications for practice are discussed. (Contains 5 tables.)