The most important discoveries of the 20th century exist not in the realm of science, medicine, or technology, but rather in the dawning awareness of the earth's limits and how those limits will affect human evolution. Humanity has reached a crossroad where various ecological catastrophes meet what some call sustainable development. While a great deal of attention has been given to what governments, corporations, utilities, international agencies, and private citizens can do to help in the transition to sustainability, little thought has been given to what schools, colleges, and universities can do. Ecological Literacy asks how the discovery of finiteness affects the content and substance of education. Given the limits of the earth, what should people know and how should they learn it?