This document offers guidance on planning, developing and implementing digital interventions to promote better health among adolescents and youth. It includes the key steps in each stage and the unique aspects of designing such interventions with and for young people. The Introduction briefly covers the history and landscape of digital health interventions for young people and how this document was developed. Chapters 1 through 3 lay out an overarching framework, fundamental principles and cross-cutting actions for successful planning, development and implementation, respectively. Chapters 4 through 6 each focus on one key stage in the process, including examples of current practices, tips and warnings, and case studies from leaders in the field.