This report identifies the four components of youth apprenticeship programs and how they fit together to offer a set of principles for adoption that improve program quality. These distinguishing components are 1) structured and paid on-the-job learning under the supervision of skilled mentors, 2) classroom-based or technical instruction aligned to the workplace environment, 3) ongoing assessment, and 4) attainment of portable, industry-recognized credentials. To illustrate these components, the report presents the Aerospace Joint Apprenticeship Committee (Washington State), the Charleston Regional Youth Apprenticeship program (South Carolina), and Early Care & Education Pathways to Success (California).