This thesis seeks to review Urban Sustainability in cities of the Developing South within the broader spectrum of Sustainable Development. Notably, the Developing South has for many years struggled to embrace Sustainability in its general terms: in part, because of the fragile institutions that cannot be counted on to uphold sustainability in the truest sense of the word; and in part because of the numerous challenges that often distract any attempt to prioritize Sustainable Development. Sustainability then becomes an option in the midst of other options, rather than an option that should affect all other options. Narrowing it down further to matters urban makes it even stranger in a host of cities across the Developing South. It is against this backdrop that this study seeks to examine in depth the contextual challenges that have invariably stood in the way of Sustainable Development across the Developing South. While it may not be practically possible in a four-month study to offer outright solutions or recommendations that could address these challenges in entirety, this study nevertheless has endeavoured to stay true to the realities that are often ignored whenever challenges of Sustainable Development are mentioned on global platforms. Among these realities is the reality of slum presence in most cities of the Developing South that existentially complicates any equation for urban sustainability ever formulated to provide a way out or forward for these cities. State governments understand this too well, and so do Civil Society Organizations (CSOs) and international organizations alike involved in the crusade for improved living conditions for city resident, and in particular slum residents. Yet the State governments have never been as resolute in their quest for slum free cities. The question then remains: exactly what are the sustainable approaches for this noble cause? While the State governments have over the years insisted on enforcing conventional approaches (that include forced evictions, relocations and/ or redevelopment); one international network, however, thinks and responds differently to slum situations. The network is Shack/Slum Dwellers International (SDI). It is considerably this network of slum dwellers and their undeniably innovative approach to urban sustainability and inclusivity that largely frames the direction and general content of this study. Specifically, the methodology adopted in the study is one of a Case study - which in this case is SDI; and two separate Cases, namely Railway Relocation Action Plan (RAP) in Nairobi, Kenya and slum Re-blocking project in Joe Slovo, Cape Town, South Africa, respectively - as typical cases that captures in large part the enormous contribution that SDI is making towards inclusive and sustainable cities in the Developing South. In the discussion part, however, the study introduces Soft Systems Methodology (SSM) as a comparative methodology to SDI’s approach. SSM particularly benefits from LUMAS model and Social Learning – both key components that potentially reserve a dynamic capacity to enriching SDI’s approach as a future reference methodology for urban sustainability and inclusivity.