Implementers of market-based sanitation (MBS) interventions have a vested interest in creating a competitive supply of toilets in India. To do so requires them to improve the viability of sanitation enterprises in the market. Implementers, however, often lack an understanding of enterprise viability. What factors determine the viability of sanitation enterprises beyond sales volumes? What can implementers do to improve the viability and sustainability of enterprises? FSG conducted interviews with more than 60 sanitation enterprises across 3 countries to answer these questions. We also authored a guidance report for practitioners on creating viable and sustainable sanitation enterprises. The publication is supplemented by three case studies that detail our research on enterprise viability in Cambodia, India, and Nigeria. The research was funded by USAID and published by the Water, Sanitation, and Hygiene Partnerships and Learning for Sustainability (WASHPaLS) project.