For many years, mathematics research has focused on finding ways to help students improve their math performance. These efforts have led to the conclusion that building a strong mathematics foundation is associated with greater achievement across time. Students who develop number sense and learn to use efficient strategies at an early age are more likely to perform better in mathematics. Further, these students are able to apply the strategies they have learned to more advanced problems as they continue their mathematics education. This study explored the differences in strategy use by students with differing levels of math achievement. Specifically, it sought to understand whether there were notable differences in strategy selection, recognition, and execution between high-, average-, and low-performing students, and if so, what factors might have contributed to these differences. The results suggested that there were significant differences in strategy selection, recognition, and execution between students with different math performance levels. Therefore, future research should continue to examine the factors that contribute to strategy use differences between students and focus on understanding the development of strategy use. Understanding strategy use differences will expand researchers' understanding of mathematics learning and help educators develop more effective instructional strategies. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]