This paper examines the influence of board diversity on the quality of environment, social and governance (ESG) performance of non-financial firms located in 4 Asia-Pacific countries with divergent corporate governance structures: Australia, Indonesia, Malaysia and Thailand. The specific board diversity characteristics we consider include their nationality mix, gender, age, generational grouping and a firm's overall level of independent directors. Our empirical results suggest that board independence is vital for ESG in Australia, and less so in Malaysia and Thailand, but not Indonesia, because of its' dual board system. A diverse nationality-mix of directors mattered in Australia for Environment. Female directors support ESG initiatives in Australia and Malaysia, but male directors had a positive effect in Indonesia and to some extent Thailand. Director age is significant for Indonesian and Thailand only. GenX or GenY directors did not outperform on Environment and Social outcomes. Our oldest directors, from the Board Boomer I generation from Australia and Boomer II directors from Indonesia, supported Governance results. ESG held some positive relations with firm performance in Malaysia. Having a diverse board, therefore, does matter in regards to ESG, but results vary by country.