








A widely cited report by the federal Government Accountability Office found that charter schools enroll a significantly smaller percentage of students with disabilities than do traditional public schools. However, thus far no hard evidence exists to definitively explain or quantify the disparity between special education enrollment rates in charter and traditional public schools. This article uses student-level data from Denver, Colorado, to map the creation and growth of the special education gap in elementary and middle school grades. The gap begins because students with disabilities are less likely to apply to charter schools in gateway grades than are nondisabled students. However, the special education gap in Denver elementary schools more than doubles as students progress between kindergarten and the fifth grade. About half of the growth in the gap in elementary grades (46%) occurs because of classification differences across sectors. The remaining 54% of the growth in the gap in elementary grades is due to differences in student mobility across sectors. However, the gap does not primarily growand in fact tends to shrinkdue to the movement of students with disabilities across sectors and out of the city's school system. Rather, the impact of student mobility on the gap is driven primarily by nondisabled students: Regular enrollment students are more likely to enter into charter schools, thus disproportionately reducing the percentage of students with disabilities within the charter sector.
