The purpose of this mixed methods descriptive case study was to explore teachers' racial awareness about Black and Asian identities through race-based professional development (PD) and implicit racial bias. Teachers unintentionally bring implicit biases into the classroom experience which can impact student racial identity development. This study recognized that implicit biases can be interrupted through ongoing learning opportunities for teachers. This researcher examined how race-based PD experiences can vary depending on teachers' implicit associations of Black and Asian identities, using the Implicit Association Test (IAT) at a single sex independent high school in Southern New England, Connecticut. To situate the study, three research streams were explored: (1) teacher role in student racial identity development; (2) implicit racial bias in teachers; and (3) race-based PD for teachers. This study aimed to investigate the following overarching research question: What is the relationship between race-based PD and implicit racial bias in teachers? The sub-questions to the overarching research question were investigated through a qualitative approach using semi-structured one-on-one interviews and a quantitative approach using chi-square and one-way analysis of variance (ANOVA) tests. Findings from the study suggest: (a) Teachers may be able to articulate their awareness around their own implicit racial biases; (b) Teachers have varying race-based PD needs; and (c) External factors may influence teachers' engagement in race-based PD experiences. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]