Background: Across the world, many young people are supplying unpaid, informal care. There is growing evidence of the impact of this caring role on the lives of young informal carers, however there has been little quantitative analysis of the mental health impacts. This research aimed to estimate the effect of informal caring at age 14/15 years on mental health at age 18/19 years. Method: Data was drawn from Waves 5, 6, 8 (2012-2018) of the Longitudinal Study of Australian Children.