How did ambitious projects of wetland improvement give rise to a new kind of environmental politics in early modern England? This chapter first asks how such projects reconfigure understandings of when, where, and how environmental change took place in this period. Environmental acts were political, it argues, because they relied on and engendered relationships of power: decision-making institutions, laws, legitimacy, and – above all – negotiation and conflict. It next explores what kind of politics were at work in imagining, implementing, and contesting wetland improvement. In emphasising material and institutional progress, studies of ‘improvement’ and ‘the state’ have often overlooked the contingent processes through which productivity and power were made and disputed on the ground. Mobilising custom as a practice and right, wetland communities played a vital role in the trajectory of improvement. Conflict over improvement exposed the contested nature of political authority in seventeenth-century England and generated material landscapes of flux. Finally, this chapter examines how speech acted and actions spoke to remake wetlands via print, maps, institutions, and environments.