This dissertation examines the environmental changes that attended the founding of the colony of Pennsylvania and its capital city of Philadelphia in the latter part of the seventeenth century. Through engagement with the analytical methods of environmental history, ethnohistory, and ecocriticism, this dissertation demonstrates that environmental change was a vitally important factor in a series of conflicts among the various peoples of early Pennsylvania, and explores the ways that people changed their own social arrangements by changing their environment. The central conflict, the contest around which the others revolved, concerned the founding of Philadelphia. The idealistic aspirations of colonial proprietor William Penn, who envisioned (in various forms) an expansive and planned settlement designed to promote good social order, clashed with the motives of Pennsylvania’s colonists, who wanted a port city that would most efficiently facilitate the export of the colony’s agricultural production. The outcome of the conflict over the nature of Philadelphia was decisive: the colonial city was indeed, in form and function, primarily a node that served as the vibrant interface between Pennsylvania’s fertile agricultural landscape and the larger Atlantic economy. The conflict over the nature of the city also shaped the nature of the larger colony. Pennsylvania was primarily a project of environmental transformation, as colonists eagerly implemented an English-style agricultural system rooted in private property ownership and production for the Atlantic economy. This process of environmental transformation was especially consequential for the nature of relationships among the people of the colony. The new ecological regime of Pennsylvania served as a mechanism of integration that bound together diverse inhabitants of the colony (including the English colonists who made up the majority of Pennsylvania’s settlers, non-English newcomers, and the Euro-American peoples who already occupied the land before Pennsylvania was founded) into a shared system of land use, property ownership, and market economics. At the same time, in a simultaneous process, the new agricultural system alienated the Lenape people from Pennsylvania, as the dominant land-use practices of the colony threatened to intrude on Native American independence, cultural integrity, and self-determination. Environmental change therefore contributed significantly to developing concepts of identity in early Pennsylvania that saw the increasing differentiation of Native Americans and European colonists into separate categories of people, with increasingly incompatible ecological modes and systems of land use. / History