Sustainable Human Development in the Twenty-First Century is a component of Encyclopedia of Human Resources Policy, Development and Management in the global Encyclopedia of Life Support Systems (EOLSS), which is an integrated compendium of twenty Encyclopedias. The volume of Human Development examines the state and nature of human development and identifies factors that determine its promotion for the twenty-first century. A general goal, since the ultimate goal for human development is to enhance the quality of human life. However, the concept “quality of human life” is not well defined. It is determined by a set of interrelated factors that cut across many disciplines with varied perspectives and paradigms. These include the prevailing culture, health status, economic performance, technological development, political and social conditions, the building of human capacity and capabilities, and institutional development on the local and global levels. For example, in an environment characterized by a better quality of human life, it is expected that people will be able to lead long and productive lives. They are also expected to enjoy good health, have access to knowledge and educational opportunities, and be treated by all with respect, in a socially equitable and dignified manner. In the sphere of political economy, they are expected to have the opportunity to participate in governance decisions that affect their lives and the community in which they live; and to have the potential to earn sufficient income to supply themselves with adequate nutrition, shelter, and other material and aesthetic needs. Furthermore, people are expected to maintain a sustainable environment and equitable social contracts across space and generations, especially in the context of the evolving global governance. The volume of “Sustainable Human Development in the Twenty-First Century” is divided into five topics which are then expanded into multiple subtopics, each as a chapter presented in two volumes. The first is “Major issues in Human Development” and provides an over view of the Topic with emphasis on the sociological foundation of human development. The second Topic, “Diversity and Historical Processes” reviews the historical and technological processes which have led to the present state of human diversity and differentiation. The third Topic, “Causes of Global Change” focuses on whether it is possible in the present global environment to enlarge people's capabilities so that economic progress may be translated into a multidimensional human happiness. The fourth Topic, “Consequences of Global Change” examines global change not in the narrow sense of short-term economic change, but rather as historical waves of long-term development. The fifth Topic on Planning Strategies reviews current practice and projects challenges in the next century. These two volumes are aimed at the following five major target audiences: University and College Students, Educators, Professional Practitioners, Research Personnel and Policy Analysts, Managers, and Decision Makers and NGOs.