Background/Context: Policy makers and scholars have long called for the large-scale recruitment of teachers of color, partly based on evidence highlighting the positive effects of racial/ethnic matching between students and teachers of color on various student experiences and achievements. A more nuanced understanding of racial/ethnic matching effects moderated by contextual factors may help policy makers' and administrators' assignment decisions on how to consider student and teacher race/ethnicity. Purpose/Objective/Research Question: This study examined the contextualized effects of racial/ethnic matching between high school students and teachers, focusing on the urbanicity of schools in the United States, by asking two main research questions: (1) What are the associations between the racial/ethnic matching of students and teachers, and students' math achievement and self-efficacy in the United States overall? (2) What are the associations among racial/ethnic matching, math achievement, and math self-efficacy in urban schools, and do these patterns differ for suburban and rural schools? Research Design: This study used restricted-use national longitudinal data provided by the NCES High School Longitudinal Study of 2009. A strategy of disaggregating data by schools' urbanicity and three separate analyses with fixed-effect models for each urbanicity (urban, suburban, and rural) was followed to capture the variations across different schools' urbanicity and to obtain unbiased estimates of racial/ethnic matching effects. Findings/Results: Relatively lower percentages of Black, Hispanic, and Asian students were matched with their same-race/ethnicity math teachers compared with White students in all communities. This study found no supporting evidence for positive associations between racial/ethnic matching and math achievement scores and self-efficacy without considering urbanicity. Within the context of urbanicity, positive associations for math achievement were mainly found in the racial/ethnic matching of Black and Asian students taught by same-race/ethnicity teachers in suburban schools. Conversely, the racial/ethnic matching among Asian students and teachers in rural schools was significantly and negatively associated with both math achievement and self-efficacy. Conclusions/Recommendations: By focusing specifically on schools' urbanicity contexts, policy makers and education leaders should consider the relatively lower percentage of racial/ethnic matching between Black students and teachers in suburban schools, and Hispanic students and teachers in rural schools. As rural Asian populations grow and diversify, Asian teachers from diverse cultural backgrounds are urgently needed in these communities. Contextualized policy solutions that consider school environments and cultural differences and that challenge the one-size-fits-all approach will ultimately better address the specific and diverse needs of students of color living in different communities across the United States.