What happens when a comprehensive right to free movement meets national welfare systems? If we look at the contemporary EU we can begin to see at least part of the answer and the resultant unstable social and political equilibrium. Free movement for goods, capital and services as well as people – the so-called four freedoms – has been a key component of the EU's identity as an international organization since its foundation in the 1950s and is closely associated with economic integration. A positive ideology of free movement linked to a radical experiment in open borders is uneasily coupled with a continued attachment in member states to social solidarity and cohesion associated with national welfare states. Trying to square this circle has unleashed new political dynamics that challenge the European project. This chapter links the contestation of free movement to perceived effects on welfare,declining trust in politics (which itself is linked to immigration) and as a factor underlying growth in support for Eurosceptic, populist and extreme right political parties. The political sensitivity of the issue was made crystal clear in a joint letter (Austrian Federal Ministry of the Interior et al., 2013) sent in summer 2013 by the Austrian, German,Dutch and UK interior ministers to the Council Presidency calling for action to combat 'the fraudulent use of the right of free movement' and the resultant 'excessive strain on the social systems in the receiving societies'. Reactions to the letter revealed dividing lines within the EU, with newer member states as well as Sweden describing the letter as unjustified scaremongering. The EU Commission called on the letter-writing governments to produce evidence of such welfare abuse and said that the claims did not reflect the EU's own statistics (ibid.). In 2013 the Commission actually set out new actions to boost citizens' rights, based on statutory entitlement to freedom of movement. Jean Claude Juncker, Commission President since June 2014, made it clear anew that free movement was a core principle of the EU and not an issue on which he was prepared to make concessions. Opinion research shows that the right to free movement remains highly valued not only by EU technocrats but also by EU citizens themselves. According to the Eurobarometer, the 'freedom to travel, study and work anywhere in the EU' ranks year after year among the most important issues related to a united Europe (Recchi, 2015: 1). Hence, as Recchi (ibid.) points out, it is not 'the euro, nor democracy, nor peace among nations, but rather free movement which epitomizes the EU in the minds of Europeans', as shown, for example, by 2011 Eurobarometer data showing that 48 per cent of respondents across the EU see it as the most important right attached to EU citizenship (Eurobarometer 2011). This chapter surveys both the origins and more recent contestation of free movement with a particular focus on interactions between free movement and welfare. It focuses on developments in the UK and Germany to show how opposition to free movement and to the EU (albeit of very different types) has coalesced within new political movements that can challenge mainstream views on the 'European project'.