This article assesses why Eurosceptic national parties form groups in the European Parliament and examines in what ways two of these groups – the European Conservatives and Reformists and Europe of Freedom and Democracy – operate in the European Parliament. It draws on interviews with politicians and group officials, roll-call votes and expert judgement data. We look at the group formation process with a focus on the British Conservatives and UK Independence Party and find that the European Conservatives and Reformists group was created with a mixture of policy-seeking and party-management aims. The UK Independence Party's interest in the Europe of Freedom and Democracy group is largely on the basis of the group's provision of distinct practical advantages, such as resources for political campaigns. We provide evidence that hard Eurosceptic and regionalist niche parties in the European Parliament struggle to agree with each other in roll-call votes on a range of subjects. Finally, we show that the hard and soft Eurosceptic parties studied here go about policy-seeking in different ways in the European Parliament in line with their differing principles on the integration process.