This report provides a description of the development process, field testing, and psychometric properties of a student mathematics test designed to assess grades 1 and 2 student abilities. The test was administered to 2,373 participating grade 1 and 2 students in 22 schools located in 2 public school districts in Florida during fall 2013. Focused on counting, word problems, and computation, the student assessment was designed to serve as a baseline measure of student achievement in a randomized controlled trial evaluating the impact of a teacher professional development program called Cognitively Guided Instruction (CGI) on student learning.