The study aimed at evaluating the effectiveness of cooperative learning method in the subject of English. This study was focused to find the effect of cooperative learning and traditional learning on the achievement in reading comprehension and achievement in writing ability of the students of class VIII in the subject of English. It was an experimental study in which cooperative learning method was compared with traditional learning method. Cooperative learning refers to instructional strategy in which pairs or small groups of learners with different levels of ability work together to accomplish a shared goal. The aim of this cooperation is for learners to maximize their own and each others’ learning. Government Comprehensive Boys High School Rawalpindi was selected as a sample through purposive sampling. Students were divided equally on the basis of teacher-made pretest scores. Low achievers, high achievers and average students were divided in both the groups equally. Sample size was 128, Sixty-four students were included in experimental group and sixty-four students were placed in control group. Pretest, posttest equivalent group design was xviused. Treatment of planned cooperative learning technique (STAD) was provided to experimental group while control group was taught by using traditional learning method for a period of 56 days (eight weeks). At the end of the treatment, a teacher made posttest was administered to measure the achievement in reading comprehension and achievement in writing ability of the students. Same teacher taught reading and writing skills to both the groups. One with cooperative learning method and the other with the traditional learning method. Five lessons from the textbook for 8 th class were taken for reading comprehension. Thirteen exercises from grammar book for 8 th class were taken for writing ability. To determine the effect of cooperative learning method on achievement in reading comprehension and writing ability the significance of difference between the scores of groups at 0.05 level was tested by applying t-test and analysis of variance. Data analysis reveals that both the experimental and control groups were almost equal in reading comprehension and writing ability at the beginning of the experiment. The experimental group outscored significantly the control group on posttest showing the supremacy of cooperative learning method over traditional learning method. Hence, the ultimate result of the study indicated that cooperative learning method was more effective for English as compared to the traditional learning method. Furthermore, cooperative learning appeared to be more favourable for overcrowded classes.