The goal of the evaluation was to measure the sustainability of water and sanitation interventions in rural areas funded by the Water Supply and Sanitation Program for Small Communities. The evaluation focused on ensuring that the quality of these services could be maintained long-term at technical, financial, and operational levels. By sustaining this quality over time, improvements in health indicators for the population could be achieved. The evaluation identified factors and good practices correlated with higher sustainability levels in the systems constructed in 100 rural communities in Paraguay's eastern region.