The paper addresses the issue of how residual spaces are intervened upon through formal and informal processes.It argues that a profound understanding for the dynamics of informal interventions,denoted by appropriation,could enhance the performance of their formal peers.Adopting a qualitative approach,the paper departs from Lefebvre’s unitary theory of space and arrives at an analytical framework that helps to understand the appropriation processes in residual spaces.It,then,attempts to empirically challenge the applicability of this framework through analyzing a Cairene residual space that has undergone two cycles of intervention:a formal and informal one.