Despite advances toward equity, mathematics education continues to be entangled with deficit discourses at every level. Here, we analyze the webs of meaning that comprise deficit discourses. We show how these discourses are supported by seemingly neutral narratives about what counts as mathematics and narratives about students from marginalized groups. Drawing on social, cultural, historical, and political perspectives, we advance a framework that illuminates how deficit discourses are mutually reinforced across multiple layers of social organization. Examining the systemic nature of the reproduction of deficit discourses is essential for understanding why they persist in mathematics education and society more broadly.