18 th World IMACS / MODSIM Congress, Cairns, Australia 13-17 July 2009 http://mssanz.org.au/modsim09 Models of Sustainability Todorov, V.I. 1,2 and D. Marinova 2 1 University of Forestry (UF), Sofia, Bulgaria 2 Curtin University of Technology, Western Australia Email: vtodorov@ltu.bg and d.marinova@curtin.edu.au Abstract: The paper presents a general classification of the models being developed in the area of sustainability arguing that the existing models represent the historical conceptualisation of sustainability starting from environmental constraints and moving towards economic valuation and social behaviour and policies. Coupled with computer power, sophisticated models with a varying levels of complexity have also been developed (static/dynamic; local/global; specific/general). However as any model is a simplification of the complex reality, the main purpose of any sustainability modelling should be to allow for co-evolution to be represented, including the role of humans as sustainability guardians. Keywords: sustainable development, sustainometrics, co-evolution, classification 1216