In most cases throughout the world groundwater and surface water are intimately linked through the hydrologic cycle. More importantly, there are strong institutional and economic imperatives to plan, develop and manage groundwater and surface water in an integrated manner. Significantly increased water use efficiency can be achieved. Surprisingly, this has seldom occurred. Hence this chapter presents the compelling reasons why this must occur for the future use of the world’s total water resources. The significant difference between unplanned and planned conjunctive use (the latter as a component of conjunctive water management), and the approach governance must take to maximize the potential benefits from such use, is explored. The differences in management between highly connected and poorly connected systems are explained. In the highly connected case the potential for double counting of groundwater and surface water is evident. New institutional structures are usually required to achieve effective conjunctive water management. This includes policy, legislation and planning reforms, including the use of a broad range of market based and financial instruments. A suggested set of principles to achieve good conjunctive water management governance is proposed. A powerful technique that embodies the advantages of conjunctive water management is Managed Aquifer Recharge. This is used to address aquifer overdraft, meet seasonal supplies and to increase drought resilience of groundwater through water banking. The world cannot continue to ignore the considerable economic and social advantages of planned conjunctive water management.