Information technology and globalization are two main forces that will bring in a social transition in the new millenium. Human Ecology, as a discipline to study the interaction between individuals and families and their environment, needs to define a new mission in changing social environments. This paper analyzes the forces behind this social transition and their influences to the lifestyle of individuals and families. It also defines new missions of Human Ecology in terms of education, subjects and methods of research, and public responsibilities. As the society changes, the paradigm of Human Ecology should be expanded to cover newly appearing environmental factors. It should be emphasized that these expanded areas should be under the unified field of Human Ecology to offer the integrated approaches that other specialized field may not offer.