This article delineates the development of a measure to assess teachers' reported engagement in practices that center on issues of racial equity as part of their SEL instruction. An iterative mixed-method approach included theoretical grounding, literature reviews, content expert evaluation, focus groups, cognitive interviews, and multiple survey administrations. Exploratory and confirmatory factor analyses were conducted using data from three independent samples of fifth- to eighth-grade teachers (N range = 240-260; White = 67-89%; Black = 3-7%; Latinx = 5-23%). Test-retest reliability was assessed in a fourth national sample from the RAND American Education Panels (N = 482; Black/African American = 19.9%, Latino/Hispanic = 16.2%, Asian/Asian American = 2.7%, American Indian/Native American = 1.9%, White = 66.0%, Middle Eastern/North African = 0.6%, and Other = 2.7%). Results suggest (1) evidence of strong internal consistency for the 41-item Racial Equity-oriented Social Emotional Learning (REQSEL) measure; (2) REQSEL scores correlated with multiple relevant measures of teachers' beliefs and behaviors regarding race, ethnicity, culture, and social justice; and (3) REQSEL scores correlated with teachers' own ethnic-racial identity beliefs.