Over the past three decades, children from low-income families have increasingly been attending different public schools than those from more affluent families. Though recent work has helped us understand patterns of income segregation between districts and schools within districts, we know little about segregation of students as they experience school: in the classroom. We attempt to advance knowledge of segregation of students by income at the classroom level. We use data from North Carolina that includes information on classroom assignments and students' economically disadvantaged (ED) status. We assess whether ED students are clustered/segregated into different classrooms than other students. We find that within-school segregation rose by about 10% between 2007 and 2014 in elementary and middle schools we study.