The chief premise of the book is that everyday actions of humanity are neither consistently honest nor criminal, but rather weasel. He dissects the aspects of weasel behavior and explores its benefits and ramifications, sometimes referring to his own life experiences. The book is divided up into many sections and chapters which show different types of weasels, how to be a weasel, weasel words, and methods for countering the weasels you may encounter in everyday life.
The book was largely considered to be a rehash of Adams' other books, most notably The Dilbert Principle. Sales were further hampered by the backfiring of Adams' announcement that he would dedicate a strip to Dilbert having sex if the book became the number one seller on Amazon.com, a marketing promotion that Adams himself characterized as "what will someday be hailed as the worst idea of the century." The book is inspired by many large companies' work environments (with reference to the Corporate Culture and Mission Statements)