The subject of the use of the existing is nowadays a necessary part of thinking about architecture in the context of sustainability and ecology. What we have is often perceived as a limitation to be adapted to—this article tries to counterpose this phenomenon and thus to see it as a potential. The article works with the notion of architectural conversion to look at the possibilities of reusing the unused, focusing on the potential of the in-between time, i.e. the phase between the unused space and its new function. It is this in-between time that offers the space to temporarily grasp the problem of empty spaces. This research explores the concept of a temporary change in the function of a space that is planned and will not be repeated. Temporary conversions emerge as a likely potential strategy for revitalising vacant spaces and promoting community engagement. The article analyses case studies of temporary conversions from Europe to understand their impact on local communities. Key findings include the potential of temporary conversions to: stimulate the community to actively engage and encourage community participation in shaping their neighbourhood, recycle used elements or materials from a temporary conversion for another purpose, add underused sites to the mental map of residents, test new concepts before making permanent changes, bring diversified forms of artistic and cultural activities to the environment, and contribute to a more vibrant and inclusive urban environment. The article also highlights the importance of considering the life cycle of temporary interventions, which is understandably mostly shorter than the life cycle of standard long-term interventions, and their potential for long-term benefits. Such conversions can continue after their end and survive their temporary existence, through positive and beneficial impact for the community.