The sheer ambition and scale of UN peacebuilding today inevitably invokes comparison with historic practices of colonialism and imperialism, from critics and supporters of peacebuilding alike. The legitimacy of post-settlement peacebuilding is often seen to hinge on the question of the extent to which it transcends historic practices of imperialism. This article offers a critique of how these comparisons are made in the extant scholarship, and argues that supporters of peacekeeping deploy an under-theorized and historically one-sided view of imperialism. The article argues that the attempt to flatter peacebuilding by comparison with imperialism fails, and that the theory and history of imperialism still provide a rich resource for both the critique and conceptualization of peacekeeping practice. The article concludes by suggesting how new forms of imperial power can be projected through peacebuilding.