Hydropower dams are at the nexus of energy and water supply and will play an important part in meeting future energy demand. An involved debate continues to surround large dam development and the methods for making hydropower development more ‘sustainable’. The research in this study considers the history of large dam construction for hydropower and the origins of the current debate over hydropower and sustainability. This provides the context for a comparison of different approaches to hydropower scheme appraisal in terms of commonly recognised sustainability assessment features. The framework developed for comparison of approaches is then applied in more detail to the International Hydropower Association’s Sustainability Assessment Protocol, in the context of an IHA initiative to develop a ‘Sustainable Hydropower’ certification label. The research shows that the IHA’s approach is comprehensive in many respects; opportunities are subsequently identified for the future development of the assessment in the context of the certification initiative.