The transition towards a more sustainable energ y supply system causes changes in the supply and demand of energ y. It requires a more flexible and efficient operation of the electricity distribution grids. It calls for a smart grid with intelligent control embedded in the grids to incorporate electricity storage and controllable loads. This will ensure cost-effective development of an efficient and reliable electricity system that allows the integration of distributed generation. To realize this smart grid, a holistic approach is needed. The issues which need to be addressed to make smart grids a successful reality are addressed in this chapter. It is illustrated that these aspects are much broader than developing and implementing technologies: a holistic approach involving all parties affected by the required paradigm shift is needed.