The OECD has been developing guidance documents and tools for the use of alternative methods such as (Q)SAR, chemical categories and Adverse Outcome Pathways (AOPs) as a part of Integrated Approaches for Testing and Assessment (IATA). However, there is a need for a systematic framework to characterise the individual biological and toxicological relevance of alternative methods in assessing chemicals in predicting toxicological endpoints. This framework could also inform their potential use in combination with other tools and methods to benefit from an integrated approach by applying mechanistic knowledge and understanding. This document outlines an approach for the use of the AOP concept in developing IATA. It builds upon the workshop held in 2014 on a framework for the development and use of IATA and experience to date with the development of IATA.