Entering the age of globalization and multi-cultures, the education system has become more accountable to provide a positive and productive learning atmosphere in which both life skills and academic skills are taught and trained. Following this welcoming trend, the present study sought to integrate a proposed critical thinking-based intervention program (3Es) on the ground of Bloom's original and revised Taxonomy (1956, 2001) into a BA English reading course. This study examined the treatment's effect on learners' critical thinking, attitudes toward L2 classroom climate, and reading comprehension in an English as a foreign language context of Iran. According to the placement test results, excluding the upper-intermediate ones left a sample of 40 (29 females and 11 males) intermediate participants being assigned to two groups: control and experimental. While the former received conventional instruction, the latter was exposed to the critical thinking program presented in three stages: exposure, exploration, and evaluation. The data were derived from Honey's critical thinking questionnaire (2004), the L2-contextualized adapted version of WIHIC (What Is Happening In The Class) designed by Fraser et al. (1986), and the British Council reading comprehension tests. After analyzing the data, the results demonstrated positive changes in the experimental group participants' critical thinking, reading comprehension, and learners' attitudes toward classroom climate after implementing the critical thinking intervention program. Our findings contribute to firstly EFL practitioners and curriculum designers, as the main authorities in revising and developing curricula and educational facilities to include the skill of critical thinking as one of the major contributors to the positive atmosphere of the class, and next to the teachers to become cognizant of the influential role of critical thinking in students' attitudes toward the classroom and their academic development.