Cost-effectiveness analysis is vital for establishing the economic credentials of interventions prior to implementation so that health outcomes are maximised. Most simulation models for economic analysis in health adopt conventional techniques that were developed for health technology assessment. System dynamics modelling is a less-used but growing approach that may be useful for contexts of complex dynamic systems, such as public health, mental health care and chronic disease prevention. This presentation will include a case study of using a system dynamics modelling approach to conduct cost effectiveness analysis of eight strategies for improving the mental health and wellbeing of children, adolescents and young people in the Australian Capital Territory.