Most cities around the world have residual spaces. Perhaps no city has no residual spaces. The residual spaces are areas in the city layout that have no real benefit to the community. These spaces appear as a result of the planning process. They are located in places such as between streets, between buildings and under bridges. Sometimes they are also called in-between spaces and lost spaces. These residual spaces seem to be a burden on city planning as they turn into abandoned or informal activities. On the other hand, they may represent a source of income and allow for community participation, which in turn could be a part of the sustainable development of cities. Therefore, these areas could be exploited and oriented towards community serving and problem-solving such as unemployment problem in developing countries in particular. In other words, these spaces have potentials that can be exploited through reuse. Tactical urbanism is a trend that seeks to reuse urban spaces and transform them into development opportunities that benefit society. Tactical urbanism mainly relies on low-cost, service-oriented projects in the community. This paper highlights the reuse of residual spaces through the adoption of tactical urbanism as an approach. In this sense, the paper identifies the residual spaces, their classification and their potentials. The paper then proceeds into determining the tactical urbanism by definition, its importance and how it works. In the analytical part, the paper investigates a local case study, “306 street" project in the Dokki area, Egypt. The study concludes the importance of reusing the residual spaces using tactical urbanism approach and their contribution to community development. The study ends with a set of recommendations on various levels.