This book aims to improve practice of environmental impact assessment (EIA) by providing information about how EIAs are, and should be, carried out. Although it focuses on the UK context in its discussion of policies and standards, the principles it discusses apply universally, as do many of the assessment methods it describes. This introductory chapter (a) summarises the current status of EIA, and the legislative background in the UK and EU, (b) explains the book’s structure, and (c) considers some trends in EIA methods.