Predefined Quality Tolerance Limits (QTLs) are mentioned in ICH E6 R2 section 5.0. As significant deviations to QTLs need to be reported in the Clinical Study Report, setting up QTLs can be challenging. In this interactive session, after providing background, we will explore questions such as: Are QTLs and KRIs related? How do you define a QTL with thresholds? How do you determine if a deviation is essential? Can you change QTLs during a study? Does it make sense to create QTLs for the study level, the country level, and the site level? How many QTLs are reasonable?