The aims of this paper are twofold: to investigate how Taiwanese teachers of English as a Foreign Language turned experiences into critical reflections via journal writings and to describe how they gauged critical reflections as teaching inquiry. The participants were 12 Taiwanese in-service teachers enrolled in an elective course entitled "Doing Teacher Research in English Instruction", meeting three hours a week for 17 weeks. Two types of data, journal entries and semi-structured oral interviews, were collected. Three levels of critical reflection -- transitions, transformations, and problematics -- were generated for further discussion. The results indicate that critical reflection as teaching inquiry helped the teachers deal with situations of uncertainty, instability, and value conflict in multiple contexts. Critical reflections enhanced teachers' understanding and brought about changes in their awareness of instructional effectiveness and teaching beliefs in their practice. For a variety of reasons, these teachers perceived critical reflections as teaching inquiry with positive and/or negative positions. (Contains 1 table.)