With fast-growing economies, defence capabilities and international interests, China and India are becoming increasingly active as contributors of public goods in international security, such as anti-piracy operations, humanitarian assistance, disaster relief, capacity-building, stabilisation and peacekeeping. This article examines the drivers and characteristics of China's and India's growing roles in contributing to security public goods. It also considers the extent to which modernisation of these rising Asian powers' conventional military capabilities is suited for these roles; the conditions under which China and India might expand such activities; and some of the possible consequences of enhanced Chinese and Indian roles in protecting the commons using military means. Those effects include potential impacts on the management of transnational security problems, the extension of Chinese or Indian geopolitical influence, the worsening of Sino-Indian strategic competition, and the ways other powers might respond, particularly in situations where China or India act unilaterally. Policy implications for existing public goods providers, such as Australia, are briefly considered.