The 25th International Congress on Modelling and Simulation (MODSIM2023) will be held at the Darwin Convention Centre, Darwin, Northern Territory, from Sunday 9 to Thursday 13 July 2023 with a workshop day on Friday 14 July. ASOR will be joining us again for the National Conference of the Australian Society for Operations Research. The International Environmental Modelling and Software Society (iEMSs) is supporting two streams and The Open Modeling Foundation is also supporting a stream. MSSANZ has held biennial congresses since 1974 that typically attract 600–900 participants.To facilitate more effective collaboration, MODSIM2023 will be an in-person event. Plenaries and Keynotes will be live streamed and available to watch free of charge. Extended abstracts will be accepted until 5 May 2023. Early bird registration is available until 31 March 2023.