The study, "The Impact of Indiana's System of Interim Assessments on Mathematics and Reading," examined the effects of using Diagnostic Assessment Tools (DAT) on mathematics and reading outcomes for students in 59 Indiana schools during the 2009-10 academic year. DAT consists of interim assessment tools--Wireless Generation's mCLASS for students in grades K-2 and CTB/McGraw-Hill's Acuity for students in grades 3-8-modified to align with Indiana's state assessments. The goal is for teachers to use the assessment results to tailor instruction to students' needs. After random assignment, schools in the intervention group received DAT, and schools in the comparison group did not receive the assessment tools or associated training. The study is a well-executed randomized controlled trial with low sample attrition. A subset of the analyses described in the study meets WWC group design standards without reservations. The study authors found, and the WWC confirmed, that the use of DAT did not have a statistically significant impact on general mathematics achievement or reading achievement for the full sample of students in grades K-8, but that the use of DAT did have statistically significant positive effects for grades 5 and 6 in mathematics achievement and grades 3-5 in reading achievement.[The following study is the focus of this "Single Study Review:" Konstantopoulos, S., Miller, S. R., & van der Ploeg, A. (2013). "The impact of Indiana's system of interim assessments on mathematics and reading achievement." "Educational Evaluation and Policy Analysis", 35(4), 481-499. Appended are: (1) Study details; (2) Outcome measures for each domain; (3) Study findings for each domain; and (4) Supplemental findings by domain. A glossary of terms is included.