This document provides an overview of environmental impact assessments (EIAs). It discusses key components of EIAs including technical, economic, environmental and social factors. It describes assessing natural environments like physical/chemical factors and biological factors, as well as man-made environments like cultural and socioeconomic factors. The primary purpose of EIAs is to encourage consideration of the environment in planning and decision making to arrive at more environmentally compatible actions. Features of the US National Environmental Policy Act are discussed, as well as various Indian environmental laws. Methods used in EIAs in developed countries are listed. The assessment process and guidelines in India are outlined in three steps.