This technical brief responds to an Arizona Department of Education request to study academic performance in schools receiving funding through the federal Title I compensatory education program, the section of the No Child Left Behind Act of 2001 governing resources for schools and districts serving disadvantaged populations. The brief describes for 2005/06-2008/09 the numbers and distribution of Arizona public schools and students across school levels (elementary, middle, high) for three school types: Title I Schools in Improvement (participating in the school improvement program, a public program to improve the academic performance of students in schools not meeting adequate yearly progress for at least two consecutive years); Title I Schools Not in Improvement; and non-Title I schools. It reports how Schools in Improvement are distributed across school improvement statuses, compares trends in reading and math proficiency for students attending each school type, and examines patterns of movement in and out of school improvement among Title I schools. Appended are: (1) Study methods; (2) Detailed school- and student-level data; (3) School-level reading and math proficiency trends, 2005/06-2008/09; and (4) Movement in and out of Title I and the school improvement program among all Arizona schools receiving Title I funding any year over 2005/06-2008/09. (Contains 2 boxes, 12 tables, 9 figures, and 5 notes.)