This paper is a partial result of a research study in a college advanced EFL reading class. The purpose of the study is to explore what Taiwanese EFL students perceive as motivational factors that may impact their critical online interactions. This paper focuses on students' group perception of factors that impact their online interactions. The factors were found closely related to a teacher's affective and cognitive support: the teacher's facilitative style, online facilitating skills, degree of familiarity with the issues, clarity of the discussion question, as well as relationships among students. Based on the result, pedagogical implications are briefly discussed for Internet-supplemented instruction in EFL classes. The result of the study recommended that the teacher's style and the environment of online discussions be open and affectively supportive with clear cognitive modeling. The paper sheds light on how EFL teachers may better integrate critical online discussions into EFL classroom practice.