We use data from a large-scale, school-level randomized experiment conducted in 2010-2011 in public schools in Indiana. Our sample includes more than 30,000 students in 70 schools. We examine the impact of two interim assessment programs (i.e., mCLASS in Grades K-2 and Acuity in Grades 3--8) on mathematics and reading achievement. Two-level models were used to capture the nesting in the data. Results indicate that the treatment effect is insignificant in Grades 3-8, and thus students in treatment schools perform as well as students in control schools. In contrast, the treatment effect is negative and significant in Grades K-2 (i.e., kindergarten and second grade), indicating that students in control schools perform higher than students in treatment schools.