Cities in diverse contexts experience increasing civil society engagement through neighbourhood-scale, informal and citizen-based interventions. Local expertise provides civil society initiatives with a notable advantage over professional planners and offers the possibility to become place-makers – and ultimately urban planners – themselves (Healey 2015; Willinger 2014). In post-industrial urban settings with large-scale brownfield sites, urban development processes can succeed in the triangle of civil society, public administration and private property owners and developers. What happens if civil society organises itself when developing ideas for a vacant site are not yet in public debate? User-generated developments, where ideas and impetus start from the side of civil society, are central to a potentially new co-creative planning culture. Collaborative, self-organised projects, such as ‘do-it-yourself urbanism’, ‘guerrilla urbanism’ or ‘temporary urbanism’ cover a voluntary engagement for the benefit of the community. Recent efforts primarily focus on how public authorities can use local knowledge (through participatory approaches, facilitation, and cooperation) or make use of the potential of these small-scale user-guided projects.