As man approached the end of the second Millennium, a complexity of problems arose mainly because of man’s ability to manipulate technology and exploit resources at a faster rate than nature could replenish. The world, for the first time, experienced major environmental challenges that called for man’s attention. Of great importance in the early 1980s were the depletion of natural resources and the menace of climate change. This automatically called for caution in the utilization of the world’s natural resources to ensure some level of sustainability. The World Commission on Environment and Development’s (WCED) report in 1987 commonly referred to as Brundtland´s “Our Common Future” marked the introduction of the concept of sustainable development in the global arena. According to this report, sustainable development is development that “meets the needs of the present generation without compromising ability of the future generation to meet their needs” (United Nations, 1987). Although criticized by many as being vague, I give Our Common Future credit for changing people’s way of thinking concerning development, environment and governance. The Brundtland´s “Our Common Future” provided the theoretical framework upon which all other conceptual frameworks instigate. Different people have attempted to give meaning to the concept of sustainable development through redefinition of the concept hence resulting into new knowledge and way of thinking about sustainable development. This essay, therefore, presents a critical analysis of the epistemological development of sustainable development theory. The development of the theory of sustainable development over the past two decades took the form of various transformations in its definition to capture different elements of sustainability as outlined in sustainable development. Since the first definition of sustainable adopted by WCED in 1987, different people and institutions alike have made efforts to provide a better definition of the concept of sustainable development resulting into different versions of the theory as analyzed below. Institutional Version The most popular institutional versions are definitions by WCED, IIED, and WBCSD. All these institutional definitions put emphasis on “need satisfaction.” While some authors criticized WCED’s definition of sustainable development as a vague conceptual framework, all the institutional versions of sustainable development borrow from the idea of Our Common Future . In an attempt to provide an elaborate definition, the International Institute for Environment and Development (IIED) expounded WCED’s definition by identifying three systems as basic to the process of development. According to IIED, sustainable development is one that maximizes on goal achievement across three systems: ecological, economic, and social (Mebratu, 1998). The IIED definition also introduces a new term, “primary environmental care” (PEC) referring to sustainability at the grassroots level. Based on IIED definition, solutions towards sustainable development must focus on the empowerment of people to be real players in their own development and protect their environment while meeting their basic needs (Mebratu, 1998). Although introduced in the late 1990s, this version of sustainable development has provided the conceptual framework for