When people must tackle a common complex challenge, you can release their inherent creativity and leadership as well as their capacity to self-organize.
Open Space makes it possible to include everybody in constructing agendas and addressing issues that are important to them. Having co-created the agenda and free to follow their passion, people will take responsibility very quickly for solving problems and moving into action. Letting go of central control (i.e., the agenda and assignments) and putting it in the hands of all the participants generates commitment, action, innovation, and follow-through. You can use Open Space with groups as large as a couple of thousand people!