This study was conducted to examine the effects of modality across gender on undergraduate student achievement when learning Algebra concepts. Cognitive Load Theory (CLT) and Cognitive Theory of Multimedia Learning (CTML) provided a framework for this study to describe in depth the concept of the modality principle. Participants were undergraduate students who were enrolled into the Elementary Algebra or the Intermediate Algebra courses for Fall 2017. The total number of participants was 108 students (74 females and 34 males). Participants joined the study as volunteers. The experiment was delivered completely online. It included two different treatments: (a) graphics and narration (GN) and (b) graphics and written text (GT). Participants were first blocked by gender and then randomly assigned into one of these two treatments. The duration of the treatment was two weeks. The dependent variable was student achievement on the posttest. The data included all participants' answers on the posttest from both groups paired with their gender. A 2x2 factorial ANOVA design was used to analyze the data in order to answer the research questions. The results of this study showed there was no significant main effect for either the modality principle or gender on student achievement. Also, no significant interaction effect between modality and gender was found on student achievement. However, the results of the independent t-test revealed a significant difference between students from the Intermediate Algebra course and those from the Elementary Algebra course, favoring the Intermediate Algebra students. The results of this study were in contrast to the hypotheses of this research, which were based on previous literature. The fact that the sample of this study was drawn from two different Algebra courses may have increased the variance. Also, the number of female students was more than the male students in this study. These facts about the sample of this study may have obscured otherwise statistically significant results. [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.]