The surge in demand for online learning, further intensified by COVID-19, has ignited profound interest in enhancing student learning outcomes in the realm of online learning. The purpose of this study was to examine how and why college students in the United States and China engaged with, accepted, and perceived online learning during and after the COVID-19 period. This study, utilizing a mixed-methods approach and amalgamating theoretical frameworks such as the Technology Acceptance Model (TAM), the Unified Theory of Acceptance and Use of Technology (UTAUT), the Theory of Planned Behavior (TPB), and the Motivation Model (MM), along with other variables, focuses on four research questions. To address these questions, a mixed-methods approach, integrating both surveys and in-depth interviews, was employed. Quantitative data collection utilized a correlational survey design, polling Chinese students in July 2023 and American students in August 2023. The survey underwent rigorous development, refinement, and validity checks, resulting in 707 valid responses from China and 324 from the United States. Data preparation procedures were executed precisely to safeguard the integrity of the analysis. Before the data analysis stage, quantitative data were scrutinized for reliability and validity, followed by descriptive and inferential statistics. Qualitative data collection featured comprehensive interviews with ten students from each nation, which were then transcribed and coded to identify predominant themes. These themes spanned the pre-COVID-19, intra-COVID-19, and post-COVID-19 phases, enabling a comparative examination of college students' experiences in both nations. According to the quantitative data from the US, the following hypotheses are supported. Hypothesis 2: Perceived usefulness significantly and positively affects attitude toward use; Hypothesis 3: Attitude toward use significantly and positively affects behavioral intention; Hypothesis 7: Perceived interactivity significantly and positively affects behavioral intention; Hypothesis 8: Perceived playfulness significantly and positively affects behavioral intention; Hypothesis 10: Motivation significantly and positively affects behavioral intention; Hypothesis 12: Attitude toward use significantly and positively affects use and acceptance; Hypothesis 13: Behavioral intention significantly and positively affects use and acceptance. Overall, the variables of attitude toward use, acceptance, perceived usefulness, and behavioral intention originate from TAM. The variable of motivation comes from MM. Perceived interactivity and perceived playfulness both significantly and positively affect behavioral intentions. According to the quantitative data from China, the following hypotheses are supported. Hypothesis 2: Perceived usefulness significantly and positively affects attitude toward use; Hypothesis 3: Attitude toward use significantly and positively affects behavioral intention; Hypothesis 5: Perceived behavioral control significantly and positively affects behavioral intention; Hypothesis 6: Subjective norm significantly and positively affects behavioral intention. Hypothesis 12: Attitude toward use significantly and positively affects use and acceptance; Hypothesis 13: Behavioral intention significantly and positively affects use and acceptance. Overall, the variables of subjective norm and perceived behavioral control come from TPB, while attitudes toward use, use and acceptance, perceived usefulness, and behavioral intentions derive from TAM. Both the TAM and TPB models are supported in the context of online learning in China. In addition, the paradigm model based on qualitative data in the U.S. context offers insights into the interconnected variables in online learning. Central to the model are the benefits and drawbacks of online learning. Students identify advantages such as convenience and flexibility, as well as technical and personal-psychological factors, while highlighting self-discipline as a key challenge. The model categorizes determinants of student satisfaction into external and internal factors, including internet quality, access to digital tools, previous online experiences, and challenges of limited in-person interaction. Attitudes towards online learning significantly influence overall satisfaction. The paradigm model based on qualitative data in China's context proposes that the online learning communication process is shaped by student autonomy, teacher preparation, and contextual factors. Effective communication strategies enhance benefits and address drawbacks, considering class participation, interaction, assignments, and academic performance. The model also acknowledges broader implications for the transition to in-person classes, student self-discipline, COVID-19's impact on learning, and diversity in online environments. The present study highlights the dual nature of online learning, uncovering both its advantages, such as flexibility and convenience, and its drawbacks, including challenges in communication and technical issues. Numerous factors influenced these experiences, with the success of online learning being credited to strong internet connectivity, adeptness in using digital tools, and efficient time management. While acknowledging constraints, including circumscribed generalizability and the reliance on convenience sampling, this study presents valuable insights for educators and researchers. Suggestions for educators include fostering favorable attitudes toward online learning, leveraging social influence, and evaluating the efficacy of technological infrastructure. Researchers are advised to explore extended-duration studies, broaden their participant selection methods, and investigate both external factors and the emotional aspects of their research. In essence, this study serves as a crucial guide for those shaping the evolving landscape of online learning, offering valuable perspectives and recommendations to stakeholders focused on improving the quality and accessibility of online learning programs. [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.]