The aim of the study was to explore the effects of cooperative learning on General Science achievement among 9th class students. Based upon previous research literature it was hypothesized that significant difference existed between the mean posttest scores of General Science achievement of experimental group and control group. The pretest posttest control group design was chosen for the experiment. The study sample consisted of 36 students of 9th class who were equally distributed among experimental group and control group, matched on the basic of their annual examination at general science scores. The dependent variable of General Science achievement was measured through self-constructed 30-item achievement test used as a pretest as well as a posttest. The experiment group was taught through cooperative learning while control group was taught through traditional teaching. The material was used such as lesson plans, worksheets and quizzes, designed to implement cooperative learning methodology. The data were analyzed through mean, standard deviation and t-test and .05 was the selected level of significance. The main result of the study was that cooperative learning method is superior to traditional method in general science achievement of 9th grade students.