What mathematics programs have been proven to help elementary students to succeed? To find out, this review summarizes evidence on three types of programs designed to improve the mathematics achievement of students in grades K-6: (1) Mathematics Curricula (MC), such as "Everyday Mathematics," "Saxon Math," and other standard and alternative textbooks; (2) Computer assisted instruction (CAI), such as "Jostens/Compass Learning" and "SuccessMaker"; and (3) Instructional process programs (IP), such as cooperative learning, classroom management programs, and other approaches primarily intended to change teachers' instructional strategies rather than curriculum or textbooks. Overall, 87 studies met the inclusion criterion, of which 36 used random assignment to treatments. These included 13 studies of mathematics curricula (2 randomized), 38 studies of CAI (15 randomized), and 36 studies of instructional process programs (20 randomized). [For "Effective Programs in Elementary Mathematics: A Best-Evidence Synthesis. Version 1.2," see ED527642.]