This monograph examines the transition of microfinance institutions to regulated financial intermediaries. By linking into the financial systems of their countries, these institutions are strengthening their ability to access international capital and capture the savings deposits of their clients and the public. From Margin to Mainstream expands upon the proceedings of a 1995 conference sponsored by ACCION that convened high-level representatives from bank supervisory agencies in Latin America and United States. Much of what is presented can be applied to work in Africa and Asia in establishing links to the formal financial sector. It aims to provide useful guidance on supervision and regulation of microfinance institutions.