Suicide rates are one of the key indicators used to monitor population mental health in the United Nation’s Sustainable Development Goals (SDGs). The Lancet Commission and Sustainable Development Report 2019 recently proposed that subjective wellbeing (measured using a questionnaire-based measure of happiness) could be an additional indicator of mental health in the SDGs. However, the extent to which happiness taps into a different component of mental health compared to suicide is understudied at the population level. In one recent study the association between suicide and happiness across communities in Hong Kong was largely explained by their close relationships with socioeconomic factors; likewise any association between national suicide rates and happiness could be due to shared socioeconomic influences on both these measures. Furthermore, the suicide happiness relationship may differ in countries with different levels of socioeconomic development. This study examined the cross-national relationship between countries’ suicide rates and happiness levels.