The Indian state has undergone significant transformation since the late 1980s, most notably the extensive decentralisation of power, with consequences for the formation and implementation of Indian foreign policy. This article explores the role of India’s constituent states explaining the extent and limitations of their autonomy and influence. It deploys and extends the state transformation approach to incorporate considerations of issue area and coalition type. Under coalitions led by typical national parties, subnational governments are less likely to influence foreign and security policy. Under the same coalition type, they are more likely to behave autonomously on non-traditional security issues such as sharing of water resources with neighbouring countries. They are less likely to behave autonomously on security issues such as the transnational expression of ethnic solidarity. Under coalitions led by atypical national parties or regional parties, subnational governments are likely to exercise a moderate level of autonomy and influence on issue areas such as transnational expression of ethnic solidarity. They are likely to exercise a high level of autonomy and influence on non-traditional security issues such as sharing of water resources. The framework is illustrated through Tamil Nadu’s activism on Sri Lanka, and West Bengal’s position on water-sharing with Bangladesh.