This study examined several aspects of Passage Reading Fluency (PRF) including performance variability across passages alternative designs for measuring PRF gain, and effects on PRF level from retesting with the same passages. Participants were 33 students from grades 2 to 10 attending a school for students with learning disabilities. PRF was measured at three test points. Time-2 tests occurred 10 weeks after time-1 tests, and time-3 tests occurred 5 weeks after the time-2 tests. At Test points 2 and 3, students read old passages (same-passage design) and new passages (different-passage design). Results showed substantial individual variation on concurrent PRF measures, smaller variation in gains measured with the same-passage design, and no passage memory effects (i.e., from retested passages). Results are discussed in relation to measuring reading gains in Response to Intervention models.