This brief examines student mobility within Kansas City Public Schools. The results reinforce earlier research on the problem and underscore the importance of ongoing efforts to reduce student mobility in the city. The findings also suggest that Kansas City's mobility problem is not just a matter of students moving between schools. Many students are leaving the city altogether to enroll in schools elsewhere. Based on five years of data on students attending district and charter schools inside KCPS boundaries, the brief finds: (1) As students progress from kindergarten to 12th grade, about half leave the system altogether; (2) Student mobility rates inside KCPS boundaries are higher than those in the metropolitan area and state. But the rates are similar to those in St. Louis; and (3) The majority of student mobility inside KCPS boundaries involves low-performing schools, but some movers "traded up," switching from a relatively lower-performing school to a relatively higher-performing school.