The conventional development paradigm assumes that the values, consumption patterns, and dynamics of the western industrial system will be progressively played out on a global scale. In this inquiry, we explore the implications of the conventional paradigm for the evolution of global energy patterns, and the compatibility with notions of sustainability. The present a global long-range conventional development scenario to the year 2050, and identify major environmental, resource, and social pressures and uncertainties. These include the economic and geopolitical consequences of fossil fuel depletion, the environmental and security implications of increased nuclear generation, the risk of significant climatic change, and the threats to social cohesion of distributional inequities. Such potential problems could negate the basic scenario assumption of steady economic and social development. By clarifying the stress points in a conventional picture of energy development, the scenario provides a useful point of departure for examining alternative long-range scenarios for sustainable energy development.