Under the current educational and societal conditions, schools face the challenge of continuously evolving. School networks can make an important contribution to this. In the project "Schools in Teams - Developing Lessons Together," a total of ten school networks for lesson development were initiated and scientifically accompanied over a period of four years. This volume presents the results of the accompanying research and the experiences of the school networks in a practical manner. It is aimed at both teachers and school leaders who wish to establish a network themselves, as well as at staff members of school administration and supervision who want to promote school networking in their areas of responsibility. The volume provides an overview of current findings in network research and reports from the ten school networks.