The outbreak of COVID-19 forced the world population to find new ways to improve their productivity. It also significantly changed the course of education and instruction entirely. Like many students worldwide, adult English as a Second Language (ESL) students have been dramatically impacted by the sudden switch to online courses due to the COVID-19 outbreak. Blended Online Learning (BOL) was considered an innovative transition for adult ESL students due to the fact that it allows the learner to view the classroom as a social learning environment, thereby strengthening their connection to the language. This dissertation aimed to investigate the online learning experiences of a group of ESL students and their instructor through online zoom classes during COVID-19. The study employed a qualitative case study research methodology. This case study utilized purposeful sampling to focus on the experiences of adult ESL students and their course instructor with learning and teaching online during the pandemic. The target population for this study was a group of 8 international adult students and their respective course instructor. Data were collected from ten field observations, nine semi-structured interviews through Zoom, field notes, and document analysis. Findings revealed that participants showed positive experiences with online learning as it had provided students with new communication forms. Breakout rooms, group discussions, and discussion boards were methods the majority of students agreed were helpful for participation while facilitating social interaction. Students printerpersoneferred to communicate with each other through online platforms as they feel safer and less shy to express their opinions. Conversely, participants showed negative experiences with the lack of reliable internet connectivity, especially in rural areas, which affected the students' ability to access online courses. Based upon the dissertation's findings, there are several practical implications for students, instructors, institutions, and administrators. Recommendations for additional research are needed to provide various observations and solutions to promote online platforms, including offering instructors training to guide students through these platforms expertly and merging synchronous and asynchronous learning to ensure a holistic learning environment for adult ESL learners. [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.]