Today, the attention on electricity transmission grids – the backbones of the United States’ and European Union’s economies – is higher than ever. These networks are getting older, are confronted with complex market liberalization processes and have to host increasing amounts of renewable energy sources. Furthermore, in order to address the challenges of energy security and climate change, transmission grids need to become ‘smarter’ by seamlessly integrating a wide range of users (generators, consumers and/or other grids). In this session, speakers from Europe and the United States will compare challenges and options for the EU and US transmission grids of the future, particularly by addressing the following questions: How much can power grids be stretched to integrate larger proportions of renewable energy? What really is a “smart” transmission grid? To what extent do the electricity systems require upgrade and restructuring to move towards smartgrid concepts? Which role can improved regulation play in streamlining the changes on grid architecture and operation? Which new technologies are available to revamp the power grid? How can we strike a balance between the deployment of new technologies and increased coordination to cope with renewables and market integration? How can transmission planning take into account possible evolutions towards distributed generation schemes?