Ecosystem models are being developed to explore a range of issues globally. This paper is currently in draft form open to comment and is being developed to provide an introduction to the CCAMLR-IWC Workshop to review input data for Antarctic marine ecosystem models. It summarises background to the use of ecosystem models in CCAMLR and the IWC and a history of the developmental work in those organisations. It also provides an outline of the nature of modelling for these purposes and the general issues that need to be considered in parameterising a model, providing input data for those models and for addressing uncertainties in this process. Lastly, it summarises the modelling platforms being developed in CCAMLR and the IWC.