How were state formation and early modern politics shaped by the state's proclaimed obligation to domestic welfare? Drawing on a wide range of historical scholarship and primary sources, this book demonstrates that a public interest-based discourse of state legitimation was common to early modern England, Japan, and China. This normative platform served as a shared basis on which state and society could negotiate and collaborate over how to attain good governance through providing public goods such as famine relief and infrastructural facilities. The terms of state legitimacy opened a limited yet significant political space for the ruled. Through petitioning and protests, subordinates could demand that the state fulfil its publicly proclaimed duty and redress welfare grievances. Conflicts among diverse dimensions of public interest mobilized cross-regional and cross-sectoral collective petitions; justified by the same norms of state legitimacy, these petitions called for fundamental political reforms and transformed the nature of politics.