Despite support for technology in schools, there is little evidence indicating whether using computers in public elementary mathematics classrooms is associated with improved outcomes for students. This exploratory study examined data from the Early Childhood Longitudinal Study, investigating whether students' frequency of computer use was related to mathematics achievement for children in third (n=7,960) and fifth (n=3,828) grades and whether teachers' instructional practices moderated this relationship. Results indicated that although prior disparities in children's frequency of computer use have been reduced, using computers had no relationship to achievement for students in third grade and was marginally (p less than 0.10) associated with lower scores for students in fifth grade. Closer examination of computer use across racial/ethnic groups found that in fifth grade, using computers at least once a week was associated with lower scores among White but not Hispanic students. Teachers' instructional practices (e.g., discussing or writing about mathematics, using materials such as manipulatives and calculators, and solving routine problems) generally did not moderate the relationship between computer use and mathematics achievement when school fixed effects were controlled, though greater differences did emerge across students based on their family income and race/ethnicity. In particular, among fifth graders living below the poverty threshold and third graders who were Black, using computers once or twice a month in conjunction with writing about mathematics weekly was associated with higher scores than either practice alone. Furthermore, using computers at least once a week was associated with higher scores among third-grade students and Black fifth-grade students who did not also solve problems from textbooks and worksheets daily. Overall, these findings suggest that policy efforts to include technology in elementary mathematics education have fallen short of their goal of improving student performance. However, it appears that using computers in conjunction with certain instructional practices may be beneficial for some children. Shifting the focus from acquiring hardware to increasing high-quality professional development may provide an initial step toward helping computer use benefit all students. [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/en-US/products/dissertations/individuals.shtml.]