In the 20th and 21st centuries oil exporting jurisdictions modernized their oil investment agreements many times in order to defend the interests of their peoples. Nevertheless, the problem of balance between defending investors'' assets and protection of interests of the local population is not yet solved and host governments continue reforming these contracts. The majority of contemporary legal theories take extreme points of view and advocate either governmental or investors'' interests. This book uses sustainable development as a theoretical framework that suggests a middle path, a way to determine, strengthen and protect mutual interests of foreign investors and host governments. Besides, it elaborates issues of rights of other stakeholders impacted by implementation of a petroleum contract. The argument of the book is focused on promotion of sustainability in PSAs. It examines development of PSAs during the past decades in four jurisdictions in support of the hypothesis that there is an evolution of these investment instruments towards sustainability, which makes these petroleum agreements better for multiple stakeholders.