The outcome of American students' performances during international comparisons consistently scoring inadequately in mathematics exposes the crisis of deficient mathematics achievement thus causing deep concerns. Learners who acquire a strong theoretical foundation in mathematics at the primary level thrived later in more advanced level mathematics curriculum; thus, instructors have pursued methods and techniques to improve mathematics achievement, particularly among primary grade school students. Research has shown that additional scholastic enhancement beyond conventional classroom instruction is crucial for kindergarten through fifth grade students. The purpose of this study was to determine the usefulness of a specific computer assisted instruction supplemental math program, Mad Dog Math (MDM), on students' math achievement as compared to students using only conventional teaching methods applied at a local elementary school located in Southern California. A quasi-experimental design was utilized. The study was intended to identify to what degree, if any, the use of the computer-assisted instruction software called Mad Dog Math was beneficial in improving students' mathematics achievement. Two classes of second and third grades, totaling 81 students ranging from seven to nine years old, contributed to the study. An experimental group (n = 39) and a control group (n = 42) participated in the study. Both pretest and posttest using the California Standard Test (CST), mathematics questions, were administered. To adjust the mean posttest scores for any preliminary difference between the groups on the pretest, an analysis of covariance (ANCOVA) was employed. The findings of this study revealed that after accounting for pretest scores, there was a significant difference between the control and experimental groups on posttest scores, F(1, 27) = 14.16, p < 0.0005 with a low effect size, partial eta squared = 0.15. However, after accounting for pretest scores, there was no significant interaction effect of MDM and gender, F(I ,76) = 4.14, p = 0.06, with a low effect size (partial eta squared = 0.001). Recommendations for future research include the incorporation of larger population and stratification of grade levels, examine the effects of Computer- Assisted Instruction (CAI) with students with learning disabilities, and to include qualitative elements such as teacher-student perceptions to expand understanding of CAI findings. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]