Using rich longitudinal data from Australia, we investigate the mental health impacts and behaviours of migration resettlement in Australia, focusing on age, gender and locus of control as possible modifiers. We find that age profiles in mental health differ significantly between migrant and native populations. Our analysis of second-generation migrants supports the ‘healthy migrant paradox’, suggesting favourable mental health outcomes. Additionally, we show that immigrants with an internal locus of control exhibit a lower likelihood of mental health issues, which suggests that an internal locus of control amplifies the beneficial effects in the case of mental health outcomes for immigrant populations.