The purpose of this explanatory, sequential mixed-methods (QUAN [right arrow] qual) study was to investigate undergraduates' attitudes toward mathematics and perceptions of a community of inquiry in the fully online (FO) mathematics learning environment. Specifically, the study aimed to learn more about relationships between undergraduates' perceptions of their online educational experiences that influence their attitudes toward mathematics. The population consisted of undergraduates enrolled in a FO College Algebra course at a four-year public university located in the southeastern region of North Carolina during the Fall 2021 semester. In Phase One, quantitative measures were used to explore undergraduates' attitudes toward mathematics, undergraduates' perceptions of a community of inquiry, and a relationship between undergraduates' attitudes toward mathematics and their perceptions of a community of inquiry in the FO mathematics learning environment. The sample (n = 30) consisted of undergraduates who completed the "Undergraduates' Attitudes toward Mathematics and Perceptions of the Community of Inquiry in Fully Online Mathematics Courses" survey instrument. The survey instrument included demographic and status characteristic items (n = 5), Attitudes Toward Mathematics Inventory (ATMI) survey items (n = 40), and Community of Inquiry (CoI) survey items (n = 34). Descriptive statistics, including mean, standard deviations, skewness, and kurtosis, and inferential statistics, including Mann-Whitney U tests, Kruskal-Wallis tests, and multiple linear regression, were calculated. In Phase Two, the qualitative phase, undergraduates' attitudes toward mathematics and perceptions of a community of inquiry in the FO mathematics learning environment were explored through a focus group consisting of four purposefully selected undergraduates who held overall high perceptions of a community of inquiry and a semi-structured interview consisting of one undergraduate who held overall low perceptions of a community of inquiry. Qualitative analysis included thematic analysis across the four domains of the ATMI and the three domains of the CoI Survey. In the mixed-methods, integrative analysis phase, data analyses procedures included descriptive analysis and connected data analysis. These methods were used to draw metainferences through the comparison of traditional quantitative and qualitative analytic methods. Findings revealed that undergraduates in the FO College Algebra courses held slightly positive attitudes toward mathematics and slightly positive perceptions of a community of inquiry. Undergraduates enrolled in FO mathematics courses value mathematics, yet they are often not motivated toward mathematics. Undergraduates with prior experience learning mathematics online held significantly more positive attitudes toward mathematics, a higher value of mathematics, and more enjoyment toward mathematics. Students' attitudes toward mathematics did not significantly differ by gender, age, and employment status; however, integrative analyses confirmed undergraduates who identified as full-time or part-time employees tend to discuss their attitude toward mathematics in relation to the convenience and flexibility of the FO mathematics course. Females with low composite attitudinal scores often described past experiences in mathematics, particularly a sense of failure, as an influencing factor toward their attitude toward mathematics. Undergraduates were most satisfied with teaching presence and least satisfied with social presence in the FO mathematics learning environment. Students' perceptions of a community of inquiry did not differ by gender, age, employment status, or prior experience learning mathematics online; however, students with prior experience learning mathematics online often compared their current experiences in the FO College Algebra courses to their prior experiences learning mathematics online. [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.]