Teaching critical literacy (CL) as an explicit intended learning outcome is essential for operating in a global and interconnected world. Considering the limited research on in-service teachers' development and enactment of critical literacy practices, particularly in second language education, this study explores a professional-development (PD) intervention aimed at promoting critical literacy practices as a pedagogical approach. A qualitative instrumental case study research approach was used, taking place in the reading classes of two high school English language teachers in a Lebanese private school. A two-stage PD intervention that focused on strategies to teach critical literacy was created. Two teachers first engaged in a two-day workshop and then in follow-up coaching and multiple implementation reflections. The data gathering methods used to determine the efficacy of the intervention included field notes from the professional-development process, pre- and post-intervention teacher interviews, and classroom observations. The findings, resulting from an iterative inductive thematic analysis approach, show how the PD intervention built on and expanded the teachers' repertoires of critical pedagogical practices in the reading classroom. The PD intervention further developed the teachers' competency in promoting learners' active participation in critical and dialogic discussions, thus enhancing students' critical thinking and stance. The findings from this study confirm the tenets promoted in the literature that systematic, on-going, context-based PD can build teachers' pedagogical resources and importantly, equip them to be able to promote critical literacy. This study concludes that practical measures for building teachers' capacity for nurturing critical literacy through an on-going and context-based PD initiative not only works, but is necessary.