One of the most widely used commercially available systems incorporating benchmark assessment and training in differentiated instruction is the Northwest Evaluation Association's (NWEA) Measures of Academic Progress (MAP) program. The MAP program involves two components: (1) computer-adaptive assessments administered to students three to four times per year, and (2) teacher training and access to MAP resources on how to use data from these assessments to differentiate instruction. This report focuses on the program's impact after the second year of implementation, and seeks to answer the following questions on implementation fidelity and student outcomes: (1) Were MAP resources (training, consultation, web-based materials) delivered by NWEA and received and used by teachers as planned?; (2) Did MAP teachers apply differentiated instructional practices in their classes to a greater extent than their control counterparts?; (3) Did the MAP program (that is, training plus benchmark testing feedback) affect the reading achievement of grades 4 and 5 students after the second year of implementation, as measured by the Illinois Standards Achievement Test (ISAT) reading scale scores or the MAP composite test scores in reading and language use?; and (4) Were there variations in the impacts of the MAP intervention on grades 4 or 5 ISAT reading and MAP composite scores across subgroups of students after the second year of implementation? The study focused on grade 4 and 5 students in 32 public elementary schools across five districts in Illinois. The differential impact among low and high ability students at grade 4 suggests that the MAP program may have the greatest impact on low and high ability students.