To succeed in today's economy, students need both proficiency in the "three Rs" (reading, writing and arithmetic) and strong applied skills. Communication skills, team work, and critical thinking have long been at the top of employers' lists of applied skills they seek in employees. States are responding to employers' needs by putting in place new educational standards. These standards include not only higher levels of basic academic knowledge that students are expected to master but also applied skills pertaining to presenting information, explaining one's reasoning, and effectively collaborating in groups. As a result, teachers nationwide are having students work in groups more frequently. This report examines a recent large-scale effort to expand a cooperative learning program in middle schools. The change in standard instructional practices gives schools a chance to not only teach students applied skills, but improve students' academic learning, if they can help teachers turn "group work" into "cooperative learning teams." PowerTeaching, a structured cooperative learning program, was designed to do just that. Thus, the expansion of PowerTeaching through a federal Investing in Innovation grant offers the education field a unique opportunity to learn what it takes to help teachers create cooperative learning environments in their classrooms. This report presents the lessons learned from this scale-up effort and findings from a multiyear evaluation of it. It describes how PowerTeaching was implemented over the first few years, how classrooms with the program differed from those without it, and whether students in the program performed better in math. The evaluation found that while teachers who taught with PowerTeaching learned to place their students into longstanding mixed-ability groups, which are thought to be conducive to cooperative learning, teachers did not consistently use the program's instructional techniques that transform group work into cooperative learning. In turn, students' math performance did not differ significantly between schools using the program and schools not using it. A likely cause for the weak implementation was that the ongoing professional development, which is an integral part of the PowerTeaching program, mostly did not occur or focused more on teaching the new material required by recently adopted education standards rather than on cooperative learning techniques. The evaluation thus points to the importance of focused, ongoing training and support when trying to modify teachers' instructional practices. This report was written with Deni Chen, Ashley Kennedy, and Joseph Quinn.