Charter schools are public schools authorized to operate with some independence from district or state public school regulations, while still being held accountable for student outcomes. Like traditional schools operated by school districts, charter schools are free and are intended to be open to all students who desire to attend. This study examined the special education enrollment gap (that is, the gap in the enrollment rate of students with an individualized education program) between charter and traditional public schools in four Louisiana educational regions from 2010/11 to 2013/14 and explored possible sources of the gap. Key findings include: (1) The gap was 2.5 percentage points (8.5 percent in charter schools and 11.0 percent in traditional schools) in 2010/11 and declined to 0.5 percentage point (10.2 percent and 10.7 percent) in 2013/14; (2) For three of the four study years the gap was largest in schools serving grades K-5, and for all four study years it was smallest in schools serving grades 9-12; (3) By 2013/14 the special education enrollment rate in schools serving grades 9-12 was higher in charter schools than in traditional schools; (4) The enrollment rate for students with an emotional disturbance was higher in charter schools than in traditional schools, but the enrollment rate for students with most other categories of disabilities was higher in traditional schools than in charter schools; and (5) Charter school enrollment was associated with an increased likelihood of a student being declassified from requiring an individualized education program, though less than 1 percent of students with an individualized education program in both charter schools and traditional schools were declassified over the study period.