The benefit of cohort studies and registries in patient-oriented collaborative research largely depends on the quality of the data collected. Health services and quality research rely on scientifically validated methods and procedures to ensure high data quality. This guideline contains recommendations for managing data quality in registries, cohort studies, and data repositories. The guideline was developed and further refined within the framework of TMF projects. In the second edition, a significantly expanded set of indicators is provided compared to the first edition, and the application of the indicators is exemplified for various types of empirical research projects. The guideline is complemented by a current literature review and analysis, making it an important component of the measures.