Drawing evidence from a survey study she conducted in her own online classes as well as from current literature, the author, who has developed and taught several MA TESOL online courses, argues that the effectiveness of online instruction is not determined by the technology but by the instructor. An effective online instructor is one who is truly devoted to the success of the learner and who understands the dynamics of virtual learning. Several factors are identified as essential for effective online instruction: clarity of course design, instructor's accessibility and presence, timely feedback, and learner's sense of learning community. The article then focuses on specific strategies, based on the author's years' online teaching experience, on how to design a well-organized online course that contains substantial instructor input; how to be an effective communicator in a virtual classroom; and how to provide timely and constructive feedback for students' academic work, especially for asynchronous online discussion, which is a major learning vehicle in an online class.