Introduction -- Validation in support of internationally harmonised OECD Test Guidelines for assessing the safety of chemicals -- Regulatory acceptance of alternative methods in the development and approval of pharmaceuticals -- Validation of alternative in vitro methods to animal testing: concepts, challenges, processes and tools -- Practical aspects of designing and conducting validation studies involving multi-study trials -- Validation of computational methods -- Implementation of New Test Methods into Practical Testing -- Pathway Based Toxicology and Fit-for-Purpose Assays -- Evidence-based toxicology -- Validation of transcriptomics-based in vitro methods -- Ensuring the quality of stem cell-derived in vitro models for toxicity testing -- Validation of bioreactor and human-on-a-chip devices for chemical safety assessment -- Integrated approaches to testing and assessment -- International harmonization and cooperation in the validation of alternative methods -- Evolving the principles and practice of validation for new alternative approaches to toxicity testing. .