This chapter focuses on a remarkable rebirth of the public trust doctrine and traces the arc of its development on the Chicago lakefront in the twentieth century. It discusses how the public trust doctrine became the primary legal rubric for resolving controversies about what is permitted and forbidden on the lakefront. The chapter then asserts that the purpose of the doctrine has changed dramatically. It was originally to preserve public access to navigable waters, in order to allow the public to engage in commerce or fishing, then the focus changed with the environmental revolution in the 1970s. Today, the purpose is understood to be the preservation of public resources in the hands of public institutions. Ultimately, the chapter analyses how the doctrine became an antiprivatization doctrine for certain select categories of public property.