Unsafe water and inadequate sanitation and hygiene in small rural communities throughout the developing world are some of the world’s most important, timely challenges. This review of small-scale and rural water, sanitation, and hygiene projects incorporates case studies that highlight best, worst, and emerging practices in the sector. Based on research and interviews with senior leaders at leading NGOs, this report recounts lessons learned primarily over the past two decades; illustrates these lessons by using case studies from the surveyed organizations; and concludes with a brief discussion of breakthrough practices identified by the surveyed NGOs.