Acid rain is a complex environmental problem which affects the United States and many other countries around the world. The United States Environmental Protection Agency (EPA) was established in 1970 to address environmental issues, such as acid rain. Through its programs, EPA works to protect human health and the environment in the United States by developing and enforcing regulations and studying environmental conditions. In addition, EPA is committed to informing the public about environmental topics and its efforts to solve them through written materials and its Web site. EPA frequently receives requests for information about environmental problems from school systems, teachers, and individuals. Acid rain is one of the most frequently requested topics. As part of EPA's public outreach on acid rain, EPA first developed this guide in 1990. This revised guide is designed to help students better understand the science, cause and effect, and regulatory and citizen action that are part of understanding and addressing acid rain. This book is intended for teachers of students in 6th-8th grade. It is written at a 6th grade level and the language, concepts, and experiments may need to be adapted for other grades accordingly. After reading the guide and doing some of the experiments and activities, we hope that you and your students will have a better understanding of acid rain and the problems it causes, as well as a greater interest in its resolution and in applied environmental science.