The performance of microfinance organisations can depend upon many factors. Current research emphasizes factors pertaining to clients, products, or broader environments. But researchers have paid less attention to the workings and internal systems of microfinance organisations. We explore how variation in performance within an organisation can alter the consequences of loans and their popularity among clients and potential clients. We illustrate with data from BRAC in Tanzania, where the arrival and rapid expansion of BRAC’s microfinance programme provides an apposite case study.