This document provides an overview of the methodology for developing guideline-based quality indicators (QIs) established by the German Guideline Program in Oncology (GGPO). This publication is intended for guideline developers, health care providers in oncology, and quality initiatives in oncology (see National Cancer Plan, goals 5, 6, and 8 [1, 2] and international methodologists in the field of Quality Measurement and Guideline development .