The thesis contributes to understanding of how the tension between social and financial performance in microfinance is assessed and managed. The dominant view at the global level favours prioritising financial performance and organizational self-reliance on the grounds that these are necessary if not sufficient for achieving sustained social impact over time. This has led to a focus in research on microfinance organizations (MFOs) that have sought transformation into registered financial institutions. In contrast, there has been less research into performance management of MFOs with strong NGO roots (referred to here as NGO-MFOs) who have prioritized social impact over growth and transformation. The thesis explores these issues for microfinance in India, starting with a systematic literature review of secondary evidence on its social impact. Two case studies of NGO-MFOs located in Tamil Nadu (ASSEFA and CRUSADE) then provide a more ethnographic perspective on social performance management and assessment. Case study data consists of participant observation, staff semi-structured interviews and organizational documents collected primarily during fieldwork conducted between 2012 and 2013. These case studies document how NGO-MFOs view the ‘best practices’ of mainstream microfinance models (including financial performance) pragmatically while conceptualizing social performance according to their core values and social movement roots. They also illustrate how the mainstream view of social performance assessment (reflected by the review of impact evaluations) fails to capture the informal, flexible, and process-oriented approaches to social performance management pursued by some NGO-MFOs