Technically feasible hydropower potential estimated at nearly 15 000 TW h/yr still exists in the world today, mostly in countries where increased power supplies from clean and renewable sources are most urgently needed to progress social and economic development. While it is not realistic to assume that all of this potential will be developed in the short or even medium term, it is clear that hydro has a substantial role to play in world energy supply. It can also offer a number of environmental and technical advantages, in terms of avoided generation based on fossil fuels. This paper reviews the current role hydropower is playing in the world, along with some its inherent benefits, and then looks at the remaining potential, and some specific development plans in various regions of the world. Attention is drawn to the advantages of developing hydropower as part of a multipurpose water resources scheme, often enabling it to subsidize other valuable functions of a reservoir or river system. It is shown that while the future major new hydro-developments will be in Asia, Latin America and Africa, there is also substantial scope for adding hydro-capacity at existing hydraulic schemes worldwide.