Language learning is an important necessity of today's globalized society. Therefore, it is vital to provide the most effective methods for learning a foreign language. Through understanding how foreign language learning, cognitive load theory, learning modalities, and participants' physiological sex relate to one another, more effective instructional strategies could be found. There were nine research questions for this study. This was a quasi-experimental quantitative study. The same included those adult Finnish-language-learners who spoke English fluently or near-fluently. At the time of the study, there were approximately 20,000 English speakers living within Finland. The independent variables were learning modalities and participants' physiological sex, while the dependent variable was the cognitive load score. The data analysis consisted of three separate two-way factorial ANOVAs. Post-hoc testing was done by Tukey's honestly significant difference. The findings were that the relationship between the two independent variables and single dependent variable was complex. In terms of descriptive statistics, males had a higher mean in the auditory-only learning modality for intrinsic (M = 3.68, p = 0.20) and extraneous (M = 3.39, p = 0.009) cognitive loads, whereas females had a higher mean in the visual only learning modality for intrinsic (M = 4.30, p = 0.012) cognitive load. In conclusion, statistically significant sex differences were found with respect to extraneous and germane cognitive loads, specifically that there was lower extraneous load for both sexes in the auditory-visual combination learning modality and that males had a higher germane cognitive load than females regardless of the learning modality. Due to the complexity of the problem, and potential for discriminatory placement, further research was recommended before changes to instruction are made. [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.]