Based on the "go to" book in the field of ecological risk assessment, this shorter, principles-based, updated textbook is essential for students and new practitioners who want to understand the purposes of environmental assessments and how to achieve them. It includes environmental risks to humans as well as nonhuman populations and ecosystems, and most types of environmental assessments. Drawing upon the author’s extensive experience in the field, first as a senior research staff member in the Environmental Sciences Division at Oak Ridge Laboratory and then as science advisor in the United States Environmental Protection Agency’s National Center for Environmental Assessment, the book explains fundamental principles and basic techniques and illustrates them with example applications which carry through multiple chapters and make this book a practical and hands-on guide. Both the content and the style are inviting and approachable to different levels of students. Features Integrates human health and ecological assessments. Includes epidemiological, risk, causal, impact, and outcome assessments. Focuses on fundamental principles that are applicable in all nations and legal contexts. Employs an engaging style and draws on the author’s practical experience. Explains fundamental concepts in short chapters, making it perfect for beginners in the field. Explains the challenges and rewards of a career in environmental assessment. This book is a practical guide for senior and graduate students in environmental sciences and management, as well as new practitioners of assessment who want to understand the purposes of environmental assessments and how to achieve them.