The growing requirement for students' robust critical thinking (CT) skills in their academic writing, particularly at the tertiary level, has augmented the attention to equipping students with CT ability. The study, therefore, sought to investigate instructors' beliefs and practices in promoting students' critical thinking (CT) in writing classes. A multiple case study design was employed to address the study objective. Three purposively selected instructors from Wolkite University participated. The data collection method involved classroom observation, interview, and document analysis. The analysis was performed qualitatively using a grounded theory approach--open, axial, and selective coding. The findings indicated that the participants interpreted CT as students' abilities to use appropriate language and logically argue in their writing. They explained some strategies used to promote students' CT skills. These included providing an explicit introduction to CT, incorporating CT into the evaluation system, scaffolding, and giving meaningful topics and adequate opportunities for students to practice writing. Writing activities such as argumentative, summary and cause-effect types were considered to promote students' CT in writing classes. The study categorized and reported factors that interfered with instructors' beliefs and practices as student-related, instructorrelated, and situation-specific factors. The findings contribute relevant insights into the English language teaching sphere.