This article defines three kinds of public/private partnership, lists their potential benefits and explains common issues and problems in their operation with examples from developing countries. It then defines and discusses the concepts of social sustainability and financial sustainability in relation to public/private partnerships, and emphasizes the importance of applying sustainability criteria to each partner. It is argued that essentially the same criteria apply to non-profit NGOs as to for-profit firms, despite their differences in goals and values. The article concludes with some suggested strategies for effective international technical co-operation in the establishment of public/private partnerships.