This study investigates college ESL instructors' experiences in teaching online ESL courses. It explores the differences in teaching focus and online modes for teaching speaking, listening, reading, and writing courses. It also investigates how ESL instructors' perceived level of technology competence varies across different online teaching modes and examines how teaching and learner engagement strategies differ depending on the instructional modality. Key findings include the observation that both BICS and CALP were prevalent in online reading courses. Although no significant difference in technology competence between asynchronous and synchronous modes was found, it was shown that instructors used more synchronous modes for online speaking and writing courses. The study also highlights that face-to-face instruction results in higher levels of teaching strategies and learner engagement compared to online settings. The study is distinctive due to its focus on online ESL teaching during the COVID-19 pandemic, providing unique insights into an unprecedented educational context. The findings offer a snapshot of the challenges and opportunities of online ESL instruction during a crisis, with implications for future ESL educator training and the ongoing development of online teaching strategies. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]