Central and State Governments in many countries have enacted laws and regulations to promote renewable energy and to encourage sustainable technologies. In doing so, they had to define what they meant by "renewable" and "sustainable", and they had to decide which particular technologies or organizations would be eligible for subsidies and tax concessions, and which others would be excluded. Not infrequently, a considerable amount of lobbying would precede the passage of such laws and regulations, and the resulting definitions of "renewable" and "sustainable" are often different than their original meaning. As a result, there now exist many laws or regulations, which define "small hydro" as renewable and sustainable, whereas "large hydro" is labeled by some of the legislators as being either not renewable or not sustainable. To further complicate matters, the definition of "small hydro" varies widely from jurisdiction to jurisdiction, from as little as I MW capacity to as much as 100 MW capacity. This article traces society's increasing preoccupation with renewability and sustainability issues over the past few decades, and addresses the question of whether large hydropower should be considered renewable and sustainable.