Led by a premise that effective cooperative tasks play a vital role in enhancing Cognitive Engagement (CE) and task achievement in ESL/EFL teaching, this study investigates the effects of Cooperative Learning (CL) on Omani Bachelor of Education (B. Ed.) students' CE and task achievement. This quasiexperimental study has three objectives: (i) To find out the level of awareness of CE skills required during EFL learning sessions; (ii) To examine whether there are any statistically significant differences between the mean scores of students' responses taught through CL strategies and taught in normal setting; and (iii) To investigate whether there are significant differences among EFL students' CE levels attributed to their gender. A total of 36 B. Ed. students were assigned to Experimental Group and Control Group with 18 students in each. Analytical results of the study found that (a) The overall CE levels of the students was low at the mean score of 2.20; (b) On statistical grounds, significant differences were found at the level of <0.01 between the mean scores of CE responses of students taught through CL and those who were taught in a normal setting; and (c) No statistically significant differences were found at the level of <0.05 between mean scores of students' CE responses attributed to their gender. We have discussed a number of pedagogical implications emerging from the findings of this study for raising students' awareness, enhancing teachers' roles and responsibilities, effective task designing and developing engaging instructional materials.