But the long-term sustainability of off-grid electrification depends on more than technology. It requires effective prioritization and planning to enable economic choices of technology, appropriate infrastructure to ensure that services are provided over the long run, and sustainable financing to make these capital-intensive technologies affordable. Drawing on some 15 years of experience in designing and implementing off-grid electrification projects in developing countries around the world, this Note offers World Bank staff and others interested in off-grid rural electrification projects guidance and insights into fundamental design principles for sustainability and sound practices for effective decision-making