The book has argued that design participation presents tried and doable inroads toward environmental and social change. This is because many environmental and social issues are structured so that multiparty knowledge coproduction, elaboration of design problems and solutions, direction search, and more widely informed decision-making are requisites for moving toward sound action. Participation matters. The matters of participation, in turn, cannot be adequately handled in a “just add users and stir” manner, as Muller and Druin nicely rephrase the old feminist dictum by Harding. Let us be clear about this. Involving the affected people in design and stirring does on occasion work at least to some length, but most of the time the matters of participation require more considered ways of acting. And while the matters of participation are elaborated across several bodies of academic literature, the predominantly prescriptive and dispersed nature by which this is done does not straightforwardly carry through to informing design participation—as practiced or even academically. Our insistence on design participation work and complementarities between different approaches to design participation are underpinned by taking design participation as one area in which democracy is rehearsed. Design, planning, innovation, and technology development have traditionally been expert-driven areas of society, in which citizen participation has remained rather limited even in democratic societies. As this has changed particularly during the last two decades—making participation part and parcel of how our current design, innovation, and transformation activities operate—it is important to keep improving these practices both for the organizers as well as for the citizenry that participates. In most sectors, there is a routine backdrop as to how participation, design, and planning have been intertwined, such as in environmental governance where the previously developed participation formats in legislated hearing procedures and appeal processes have recently become paired with forms of knowledge coproduction, opening up space for experimenting with and rehearsing design participation in, for example, planning and sectoral transformation. As democratic governance overall is under increasing attacks and threats, innovating in and rehearsing participation are increasingly important to foster wider and more deeply rooted democratic engagements. We thus close the book by explicitly elaborating how the book stands with respect to some commonly endorsed academics’ and practitioners’ positions toward design participation, while recounting the book’s most salient arguments.