This document discusses the relationship between civil society organizations (CSOs) and businesses in the water, sanitation, and hygiene (WASH) sector. It finds that while CSOs and businesses may have some differing philosophies, their roles can also be complementary. CSOs work in various aspects of the WASH private sector, including capacity building, establishing enterprises, and supply chain roles. Businesses are diverse and context-specific. Evidence from field work in Indonesia shows that while some see philosophical differences, others see social motives in entrepreneurs. CSOs can help ensure sustainability and act as intermediaries between businesses and donors or governments. Challenges include determining the right support for private sector enterprises while avoiding promoting specific