This study examined the impact of the Measures of Academic Progress (MAP) program on student reading achievement and teachers’ use of differentiated instructional practices. The MAP program is one of the most widely used commercially available systems incorporating benchmark assessment and training in differentiated instruction. MAP includes computer-adaptive assessments administered to students three or four times a year and teacher training and access to MAP resources on how to use data from these assessments to differentiate instruction. The study used a randomized design and involved 32 elementary schools in five districts in Illinois. The study found no impacts of MAP on student reading achievement or on teachers’ use of differentiated instructional practices.