How can healthcare systems be transformed by reimagining their multiple silos to favor processes and practices that are more responsive to local, horizontal initiatives? Altering Frontiers analyzes numerous experiences, using a multidisciplinary approach, paying attention to certain actors, collectives and organizational arrangements.Through this work, levers are identified that promote lasting transformation: recognizing the legitimacy of the practices of many who are often "invisible"; trusting those who know their intervention territory; investing in methodological support; taking advantage of tools and procedures such as instruments for strategic and managerial discussion; and developing the capacity to absorb innovative ideas and experiences that circulate within the environment.