This dissertation consists of two interrelated qualitative case studies. They explore transnational and cross-cultural critical friendship (CF) projects reflecting on teaching and learning activities in a face-to-face (f2f) class and an online synchronous learning environment. Various data sources of class observation notes, interview transcripts, analytic memos, and email (text) communication were collected and analyzed qualitatively.The first study was a pilot CF between an American associate professor (as the observed lecturer) and an Indonesian doctoral student (as the critical friend) at a state university in the United States. Framed under CF principles combined with the spirit of social constructivism theories, the paper sought to explore perspectives of the lecturer toward his participation in the CF, ways it might/might not help the lecturer to make positive changes in his future classrooms, and pedagogical lessons that the critical friend gained from the CF.Meanwhile, the second study examined patterns and perspectives of two American English writing instructors (as the observed instructors) of a Language Center in a state university in the United States on their participation in the CF with an Indonesian doctoral student as their critical friend. Further, the study explored how the CF supports the instructors' reflection of teaching practice and how that reflection process supports their practice, specifically in the instructional adjustment period from f2f to online learning. Framed under CF principles, together with a tenet of relational cultural theory, the study also examined the critical friend's experiences in participating in the CF and personal meanings of being a transnational and cross-cultural critical friend in the CF.The cross-case comparison analysis results appear to support key theoretical propositions of this dissertation, namely, that the CF projects, in various ways, have the potential to support the university lecturers or language ins