The thesis examines factors that influence sustainability and success of microfinance institutions in Ghana. The topic is important, particularly in poverty stricken Africa, where microfinance institutions play a significant role in supporting governments' initiatives to reduce/alleviate poverty. The developed model is tested using data collected from 14 face-to-face interviews and 114 questionnaires. The data is analysed using different techniques - descriptive statistics, cross-tabulations and regression analysis. The research design and scale of the study are appropriate to both the problem addressed and doctoral level research. A number of factors in the model developed were found to be influencing the sustainability and success of microfinance institutions. A model was proposed that seeks to offer an explanation of sustainability and success of Microfinance Institutions in Ghana. The proposed model identified five categories being: institutional characteristics, agency costs, business strategy, environment/governance and success. Single factor analysis established positive relationships between sustainability and all the five factors but placed more emphasis on three out of the five factors namely; success, business strategy and environment/governance. Multiple factor analysis established no significant differences in the sustainability with respect to the type of MFI, ownership and source of funding. Multiple Regression which allows for the testing of theories or models established a significant relationship between the Operational Self Sufficiency (OSS) and the predictors, especially the drop-out rate of clients and average loans. The Subsidy Dependence Index (SDI) was calculated for the various types of MFIs and the result was a high dependency ratio especially among the FNGOs. Though the dependency is on the decline, it is very slow indicating that most MFIs will depend on subsidies for a very long time to come. Finally it was observed that the relatively high interest rates charged by most of the MFIs tended to defeat the purpose for which the microfinance movement came about. Not only did the study confirm the research model, but it also revealed that most owners did not exhibit a deep sense of involvement and used general knowledge to practice in Ghana. The study concluded that success factors, business strategy, and environment/governance were the most critical of the sustainability factors in Ghana. It is therefore important that managers develop institutional capacities especially in managing the agency problem effectively if they have to be sustainable and successful.