The fulfillment of the role of microfinance institutions (MFIs) in providing affordable financial services to the poor is associated with invariable challenges to MFIs, particularly in maintaining MFIs' sustainability. The research work undertaken in this context to prepare author's doctoral thesis has finally culminated in a book, which has comprehensively dealt with the subject of sustainability versus poverty outreach in microfinance. Overall, the results of panel data analysis confirm that there is no trade-off between sustainability and poverty outreach of MFIs. Thus, MFIs are in a position to achieve operational self-sufficiency while expanding services to the poor. Further, it is evident from logit analysis that group lending as against individual lending is strategically important for MFIs to achieve sustainability, successfully warding off the problems of asymmetric information prevailing in the rural credit markets. The book carries a detailed description on Sri Lanka's financial sector and poverty aspects with special emphasis on microfinance sector which comprises of more than 15000 service providers under a variety of institutions with different mandates and business models. Policy discussion along with the findings of econometric analyses provides the reader with new insights especially in the absence of any other macro-level studies carried out to cover microfinance sector in Sri Lanka.