Informal settlements are a relatively new phenomenon in Yemen, first documented in the 1980s (El-Shorbagi, 2008; 2007). They have since grown at a very rapid rate. Sana'a City, the nation's capital, alone has an estimated 35 informal settlements that together contain 20.5 percent of that urban center's population (El-Shorbagi, 2008; 2007). To date, the Yemeni government has paid limited attention to informal settlements. The government has not developed any specific planning policies to address their needs, partly due to meager resources and professional capacities, and partly as a consequence of conflicting (and higher priority) needs (World Bank, 2010a). The unchecked growth of informal settlements has alarmed local and national authorities as well as international organizations and recently caused officials in these entities to begin to consider seriously how to address this new community reality. This dissertation explores the engagement of state and non-state actors in informal settlement governance in Sana'a. The analysis offered here employs Mahwa Aser, the largest and most controversial informal settlement in Sana'a, as an exemplar for a broader set of concerns for all of Sana'a\s informal communities. The dissertation provides a nuanced portrait of Yemeni government capacities, policies, and practices related to Sana'a's informal settlements generally and to Mahwa Aser particularly via the perspectives and activities of multiple stakeholders, including, importantly, the community's residents. It explores the active governance roles of non-governmental and international organizations seeking to provide services in these communities as well. It also explores ways to build informal community residents' capacities to work with government and with non-governmental organizations (NGOs), international non-governmental organizations (INGOs), and international governmental organizations (IGOs) to address their many basic needs. The analysis draws on personal interviews with key stakeholders, including long-time residents of Mahwa Aser, responsible government officials, and relevant leaders of NGOs, INGOs, and IGOs in Yemen, U.S.A., and Egypt. The author also examined government and international organization reports and documents to gain insight into the governance challenges linked to continued growth of informal communities in Yemen. The study identifies a number of factors that have led to worsening living conditions in Mahwa Aser and other informal settlements in Sana'a. Taken together they suggest the Yemeni government and its partners may need to work far more self-consciously with informal community residents to establish shared goals and clear expectations. Those entities engaged collectively in governing these communities in Sana'a and in Yemen more generally will need to develop reliable policies and coherent programs within a transparent governance framework if the very difficult living conditions in such communities are to be improved. In particular, governance actors will need to devise ways and means to develop government capacities and resources even as they work to address community infrastructure and service needs in a sometimes daunting socio-cultural and economic context. / Ph. D.