This article contributes to the analysis of the politics of nostalgia by focusing on its content, conditions, and mechanisms. Frame theory is used to understand the contested nature of nostalgia through the central framing of the past. We explore ways in which nostalgia relates to ethnic nationalism and populism and its close relationship to the rhetoric of the populist radical right. Components of nostalgia that stand out as particularly significant is the history of decline and loss. Whereas nostalgia is utilized by proponents of both civic and ethnic nationalism, we are particularly occupied with the ethnic substance of nationalist nostalgia. Nationalist nostalgia capitalizes on loss, idealization, and resentment and its contested nature may be brought out through diagnostic and anti-migrant frames. A central mechanism is the juxtaposition and unfavorable comparison between an idealized glorious past, a decaying present, and the creation of a utopian future, that in many ways resemble Christian narratives of fall and redemption. We therefore expect an increasing appeal of nostalgia as an orienting mechanism during unsettling times, rapid changes, and uncertain conditions. We draw upon critical cases of the radical right in Europe, and case studies from the Balkans, Lebanon, the Netherlands, Poland, Sweden, and the United States.