Drawing on data from a study of learning, race, and equity in an urban high school organized around specialized learning academies, we examine the ways in which the design, framing, construction, and organization of learning spaces deeply influences the types of access to rigorous learning that students experience. We draw on the notion of racialized learning pathways to examine access to science, technology, engineering, and mathematics (STEM) learning spaces and the ways in which decisions about engaging these learning settings are bound up in notions of race, racial identity, gender, and belonging. We also take up the questions of how researchers and educators can intentionally design for positive racialization toward more inclusive school organization and classrooms. This article contributes to understanding of (a) how learning and identity development are mediated by broader processes of racialization tied to schooling organization and access structures and (b) how racial and gender inequities in STEM can be both reproduced and contested in large urban schools serving racially and socioeconomically diverse students. We contribute to the literature on equity and access in STEM by attending to the racialization processes that we argue are always at work in urban schools, particularly so in schools that are organized into pathways demarcated along racialized lines.