The meaning and origin of the concepts of environment and ecology are traced. Reasons for enhanced concern for environmental consequences of development projects are discussed in the context of the basic functions of the biosphere and their relationship with man. The importance of natural environment is also brought out in the context of the need for improved "quality of life" and distinction between income and wealth. These provide a framework for discussion on various types of conflicts between ecologically sound and economically viable use of the natural resource systems, and ways to resolve them.