The House of Lords is recognised as unusual among modern party-dominated parliaments for its method of composition—comprising appointees, hereditary peers and Bishops of the Church of England. However, equally interesting but less often noted is the presence in the chamber of around 200 members who do not take a party whip. Drawn from various walks of life, including the law, civil service, academia, science and the voluntary sector, these ‘Crossbenchers’ have their own group organisation and ethos. Given their numbers, they potentially hold the balance of power in the chamber. In this paper we examine the backgrounds, organisation and political activity of the Crossbenchers, asking what impact they have on the policy and culture of the House of Lords. We also examine the recent changes in the Crossbench group following reform of the chamber in 1999—including an influx of more active peers, resulting in changing beliefs and style. We find that the Crossbenchers have a subtle and changing influence, much of which is difficult to quantify. Their presence is widely valued, and most proposals for House of Lords reform suggest that an independent element should be retained. But this raises difficult questions about how political independence should be defined, and where such members are to be found. The paper provides some reflections on the challenges to independent membership of modern party-dominated parliaments.