Whereas the literature on adaptation is rich in detail on impacts, vulnerability and limits to adaptation, less is known about governance systems that facilitate adaptation in practice. This paper offers preliminary conclusions on the constraints and opportunities for mainstreaming adaptation to climate change into water management in the Netherlands. We use the term mainstreaming for the integration of adaptation actions into ongoing sectoral planning to reduce climate vulnerability. In particular we look at the integration of climate adaptation and water management, currently underway in the implementation of the Dutch Delta Program. The Delta Program is an integral policy program executed by the Dutch Ministry of Transport, Public Works and Water Management, the Ministry of Agriculture, Nature and Food Quality and the Ministry of Housing, Spatial Planning and the Environment. The paper analyses the current implementation of the Delta program in the Netherlands according to the dimensions of the Earth System Governance framework: Architecture, Agents, Adaptiveness, Accountability, Allocation and Knowledge. The analysis suggests that all five governance dimensions are considered to capitalise on opportunities for successfully planning and implementing the Delta Program and its subprograms. Architecture gets most attention at present, but the implementation depends on the subprograms and varies over time. Program bodies generally bring together government agencies from different levels of government (national, provincial, municipal and water boards). A challenge for the new emerging program bodies is to move towards legitimate, accountable ánd adaptive governance. The program so far has little attention for coalitions of government actors and non-government actors or conferring accountability to stakeholders. One of the aims of the Delta Program is innovation of water management. At present science has few strategies analysed or tested to support this innovation. Typical advice includes encouraging innovation ...