This paper reports results from one of the first large, nationally representative surveys of non-governmental organizations (NGOs) in a developing country. The NGO sector in Bangladesh is highly organized and relatively homogeneous. Most NGOs utilize a branch and headquarters structure in which branches have limited autonomy from headquarters. At the branch level, most NGOs in the country, whether big or small, focus on credit services, derive more of their income from fees for services than from grants, rely on salaried rather than voluntary staff, keep detailed financial accounts that are externally audited, and hire middle-class college educated men as managers. The convergence to a modal institutional form probably is the result of the persuasive power of ideas, sociological pressures toward acculturation and conformity, as well as material incentives.