This study compares the effects of two methods of teaching--teacher-centered and cooperative learning--on students' science achievement and use of social skills. The sample consists of 163 female elementary science students in 8 intact grade 5 classes who were assigned to 2 instructional methods and were taught an identical science unit by 4 classroom teachers. The students' science achievement was measured by a researcher-designed achievement test given to students as a pretest and a posttest. Students' social skills were determined by a researcher-designed survey administered as a pretest and posttest. Analysis of the achievement test scores and the social skills survey responses revealed that cooperative learning strategies have significantly (p greater than 0.05) more positive effects on both students' achievement and social skills than teacher-centered strategies. These results provide an evidential base to inform policy decisions and encourage and persuade teachers to implement cooperative learning methods in Kuwaiti classrooms.