Many of today's populist radical right (PRR) leaders in Europe came through their party's youth wings. Yet, we know little about these organizations and how they support their parties. This book, which is not only the first to examine PRR youth wings, but is the first in English to look at youth wings of any ideological type, offers an in-depth investigation of their structures (organizational features, relationships with the senior party, and international networks) and agents (leaders and grassroots members). Covering ten PRR youth wings from across Europe and based on extensive interviews with over 50 PRR youth wing officials, original survey data, and document analysis, it finds that PRR youth wings are not merely peripheral future-oriented entities, but are central components of their parties in the here and now, acting as motors of mobilization, socialization, internationalization, professionalization, and normalization. The book argues that PRR youth wings function as Janus-faced institutions, supporting the populist radical right today and helping build the populist radical right of tomorrow.