This quantitative and cross-sectional study investigated the relationships between college students' perceived satisfaction of three psychological needs and learning outcomes that were measured by perceived learning gains and online learning satisfaction, as well as the mediating effects of three types of engagement on the relationships. The study collected 224 valid responses from college students in a large urban-setting university in midwestern U.S.. Participants in this study completed verified scales that measured key constructs in this study including perceived satisfaction of autonomy, competence, and relatedness, cognitive, behavioral, and emotional engagement, as well as perceived learning gains and online learning satisfaction as two indicators of learning outcomes. Data analysis was conducted in the open-source RStudio software using the "lavaan" as well as several other packages (e.g., tidyverse). The analysis results indicated that college students' perceived satisfaction of competence exerted a significant impact on their learning outcomes. However, students' perceived satisfaction of autonomy and relatedness did not have significant influence on their learning outcomes. In terms of the mediating effects of the three types of engagement, only cognitive engagement was found to have meaningful and partial mediating effects on the relationships between students' perceived satisfaction of competence and perceived learning gains. This study had theoretical and methodological implications for similar studies in the field of education. [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.]