Cobblestone Applied Research & Evaluation, Inc. conducted a two-year Randomized Control Trial (RCT) of GO Math! during the 2012–2013 and 2013–2014 school years. Teachers and their students were randomly assigned to either the treatment group (GO Math!) or the control group (the mathematics program already in place at their school). Study participants included 1,489 Grade 1, 2, and 3 students and 70 teachers from 9 schools in 7 states. When comparing the treatment group using GO Math! with a randomly assigned control group, the students using GO Math! performed significantly better than controls after two years of using the program on key student achievement measures. Specifically, students exposed to the GO Math! curriculum for two consecutive years demonstrated significantly more growth in ITBS scale scores across the two academic years (2012–2013 to 2013–2014) than students in the control group. In addition, students who were exposed to the GO Math! curriculum for two consecutive years had significantly higher standardized state test scale scores than students in the control group.