The aim of the present study has been to investigate The Impact of Cooperative Learning of Teaching Science on the Academic Achievement and Self-Concept for first preperatory Pupils in comparison with the traditional method both used in Science .A total of 150 first preperatory Students from Batinah North who enrolled in 4 sections of Balaj bin Okba Al Farahidi School participated in this sample study.Two of these sections were randomly choosen to form the experimental group, which used cooperative Learning method , while the other two control groups received the traditional method. After a six - week experiment an achievement test was given to all members of the sample study. A self- concept scale which was developed by the researcher was utilized. A Multivariate analysis of T - test was used to measure the effect of the treatment in the dependent variables ( The Academic Achievement and Self - Concept) and to measure the difference between the pre and post - tests performance of students regarding the achievement and self-concept of both the experimental and control groups. The research findings showed that there were statistically significant differences in the academic achievement of science between the experimental and control groups due to teaching method for the benefit of experimental group at the significence level of 0.05 . The finding also showed that there were no statistically significant differences among students self-concept resulting from the teaching method applied. The research findings indicated the necessity of using the cooperative learning method in teaching because of its positive effect on developing students academic achievement in Science,