For several years, an intense and controversial debate on patterns and trends of spatial practices has been going on in discourses related to urban development. In this context practices of “do-it yourself” civic engagement and self-initiated projects are highly discussed (et. all Bishop and Williams, 2012; Peck, Theodore and Brenner, 2012). Against this background a variety of different projects are developed in cooperation with local authorities, planners, architects, as well as commercial and civil society actors. Thus different actors, in addition to the classical professions are contributing to urban development and to diverse modifications of classical planning structures, with new approaches and mechanisms to adjust urban development to new challenges. They seem to satisfy the desire for participation in the production of the built environment, and are gaining power in the negotiation of new urban policies (e.g. Holzmarkt Berlin). Their claims and active enrolments are highlighting new opportunities for the developments or the testing of all conceivable forms of cohabitation, economic activity, and the use of public and private spaces. Based on a two-years research project in cooperation with the Wüstenrot Foundation on new formats of production, transformation and appropriation of urban spaces in urban development from the perspective of the “ephemeral ” (in terms of improvised, self-initiated and volatile projects) we have deepened our understanding of the patterns of current spatial practices and the actions of the involved stakeholders. Involved (civil) actors turn into experts for their own environment in terms of urban development issues. This spatial practice opposes an understanding of urban development as an issue that can only be targeted by the planning discipline. Overall, a shift in the importance of disciplinary knowledge can be recognized, thereby unlocking the locally produced knowledge in the development of projects gains importance and becomes a new challenge. Against this background the search for ways to retrieve the locally produced knowledge begins. The professional interest addresses the possibilities of the resulting development and transformation of space and the emerging local expertise which is produced in the process of communication in-between the project participants, thus the kind knowledge that derives from “adaptation” and “learning experience”.