This study examined the implementation and outcomes of cooperative learning methods in daily school life. In the context of an intervention wait-list control group research design lasting over two years, a group of Austrian students was taught using mainly cooperative learning methods in German language arts. In addition to standardized tests, self and peer report questionnaires assessed reading ability and aspects of social behavior before and after the intervention. Focus group interviews of teachers were used to investigate the implementation of cooperative learning methods in daily class life. The participants were nineteen teachers and 294 fifth and sixth graders from eight different schools at the secondary level. The results show that teachers prefer relatively specific cooperative learning methods. The results also illustrate that students who used cooperative learning methods in German language classes developed significantly better in reading comprehension than the students in the wait-list control group. However, concerning the reports of social behavior, most differences between the two groups failed to reach statistical significance.