This study used a quantitative, causal-comparative design. It compared educational outcome data from online Algebra 1 courses to determine if a significant difference existed between synchronous and asynchronous students for end-of-course grades, state assessments scores, and student perceptions of their course. The study found that synchronous students had significantly lower end-of-course grades and standardized test scores than asynchronous students. In addition, it was found that there was no difference between synchronous and asynchronous formats in student perceptions of transactional distance. Nevertheless, the findings provide valuable information regarding outcomes in online Algebra 1 courses. The study includes a discussion of the problem of online mathematics instruction, along with several research-based suggestions for improving online mathematics instruction at the high school level. Several recommendations for future research are discussed. [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.]