This Handbook was prepared for writers and reviewers of Environmental Impact Statements (EIS) in the state of Illinois. It provides a basic introduction to the preparation of these statements, and gives suggestions for content, organization, and format of presentation. This report is directed at impact statements for projects of concern at at the state, rather than local or federal, level; e. g. Reservoirs, stream channelization, highway links, mining operations, and public facility location. There are four basic sections to the handbook: Chapter 1 suggests an organization for the writing of impact statements; Chapter II reviews environmental impact assessment methods: Chapter III gives annotated examples of Impact statements; Chapter IV lists important sources of information concerning environmental effects in the state of Illinois.