Drawn from the experiences of the Cornell Youth and Work Program, a 4-year demonstration project that adapted elements of European apprenticeship in the United States and emphasized opportunities for youth to learn at work, this guide is written for people in workplaces and schools who plan, direct, or evaluate work-based learning opportunities for youth. Following an introduction that describes the demonstration projects, types of work-based learning, and the principles derived from the project, the guide contains seven sections. The sections cover the following topics: (1) technical competence (getting started, designing a multiyear program); (2) breadth (why teach all aspects of the industry, why rotate, why support projects and complex activities, what makes a good project); (3) personal and social competence; (4) expectations and feedback; (5) teaching roles (coordinating, managing, coaching, mentoring in work-based learning programs); (6) academic achievement; and (7) career paths after high school. A concluding section suggests next steps for restructuring schools and workplaces, forming partnerships, and building a school-to-work system. An appendix contains statistics and samples from the demonstration project. (KC)