Microfinance institutions (MFIs) provide credit, savings, and other financial services to the poor and must successfully manage large volumes of small transactions.  SymBanc™ is a system dynamics simulator designed to introduce students to the complexities of managing a Microfinance Institution (MFI) or to engage experienced practitioners in a discussion of the key determinants of success in such a dynamic environment.   The simulator allows students and practitioners to grow an MFI from a single branch to a large network by making a variety of decisions about target market, staffing and facilities, loan and savings product design, and sources of external funding.  Detailed feedback enables them to fine-tune their strategies during a simulation.  This paper begins with some background on Microfinance Institutions and then presents the structure of the model underlying SymBanc™ and results of typical simulations.  Initial experience using SymBanc™ and future enhancements contemplated for it are also described.