In recent years, rigorous studies have shown that effective public schools are built on strong collaborative relationships between administrators and teachers. The two largest national teachers' unions--the American Federation of Teachers and the National Education Association--have embarked on major initiatives to promote greater collaboration, supported in some cases by large foundations. Therefore, this Winter 2013-2014 issue of "American Educator" is dedicated to addressing such concerns, exploring in depth why collaboration between teachers' unions and administrators has the potential to significantly improve student achievement and strengthen the nation's school systems. It synthesizes research findings; highlights districts and schools that have intensively pursued collaboration; and provides strategies to guide teachers, administrators, and public officials interested in cooperation. It also explains "why" collaboration is critical to raising student performance, drawing from research in other institutional settings as well.