Under what conditions do young precarious workers join unions? Based on case studies from France, Germany, the United Kingdom, and the United States, the authors identify targeted campaigns, coalition building, membership activism, and training activities as innovative organizing approaches. In addition to traditional issues such as wages and training quality, these approaches also featured issues specific to precarious workers, including skills training, demands for minimum working hours, and specific support in insecure employment situations. Organizing success is influenced by bargaining structures, occupational identity, labor market conditions, and support by union leaders and members. Innovative organizing tends to happen when unions combine new approaches with existing structures.