Recent studies have established that there is a strong correlation between charter schools and school segregation. We investigate psychological mechanisms for this segregation based on the theory that charter school websites invoke racial codes to appeal to socio-demographic audience niches. We scraped websites from 5,334 charter school websites across the US and used Structural Topic Modeling to discover latent topics that significantly vary by class and race. From these models and our text data, we developed stimuli for survey experiments to provide causal evidence that textual self-descriptions (the novel manipulation of this study) influence parental judgments of schools’ quality and expected fit with their child. Our emerging body of evidence suggests that perceptions of racial demographics and school quality are indeed influenced by website content. This social dynamic encourages segregation, privileges charter schools serving predominantly white student bodies, and contradicts popular claims that market-based, colorblind educational policies improve equity and access. Our methods also illustrate how computational and experimental methods can be mixed to strengthen both internal and external validity.