Over the past three decades, children from low-income families and those from more affluent families have increasingly been attending different public schools. While recent work has helped us understand patterns of income segregation between districts and schools within districts, we know very little about segregation of students as they experience school: in the classroom. In this paper, we attempt to advance knowledge of trends in the segregation of students by income at the classroom level. We make use of detailed, student-level administrative data from North Carolina which provides a measure of a student’s free/reduced price lunch eligibility, which we refer to as economically disadvantaged (ED) status, along with information on classroom assignments. Since we know the ED status of each student in each classroom, we assess whether ED students are assigned to classes in the same pattern as other students or if are clustered/segregated into different classrooms. We know very little about the magnitude of income-based segregation, and almost nothing about whether this has changed over time, so we provide novel evidence on the question of whether segregation of students by socioeconomic status has increased within schools. We find that within-school segregation has risen by about 10 percent between 2007 and 2014 in elementary and middle schools we study. Further, we find that segregation of ED students within schools is correlated with the level of segregation between schools in districts, and this relationship grew stronger over our panel.