His best-known book, The Four Agreements, was published in 1997 and has sold about 10 million times in the United States and has been translated into 46 languages. The book advocates the personal freedom of convictions and agreements we have made with ourselves and with others, which create use and unhappiness in our lives.  It was broadcast on the television show Oprah.  The four agreements are: The Four Agreements©, were published in 1997 and have sold about 9 million times. He has been on the New York Times bestseller list for nearly a decade. Everything we do is based on agreements we have made – agreements with ourselves, with other people, with God, with life. But the most important agreements are those we make with ourselves. In the first part of this 2-part video, we learn how the “domestication” of men and how all the rules and values of our family and society are imposed on us by a system of punishment and reward. As young children, our true nature is to love and be happy, to explore and enjoy life; We are absolutely authentic. But then we learn to be what others think we should, and because it`s not normal that we are who we are, we start pretending we`re not what we`re not. When we are teenagers, we have learned to judge ourselves, to punish ourselves and to reward ourselves after agreements that we have never chosen. The four agreements help us break self-limitation agreements and replace them with agreements that bring us freedom, happiness and love.
The book is based on a series of spiritual beliefs, held by Toltec`s seniors, to help readers transform their lives into a new experience of freedom, happiness and love.  According to the author, everything a man does is based on agreements he has made with himself, with others, with God and with life itself.  In these agreements, we can tell ourselves who they are, how to behave, what is possible and what is impossible.  Some agreements that create individuals may not cause problems, but there are certain arrangements that come from a place of fear and have the power to deplete emotional energy and reduce a person`s self-esteem.  The book states that these self-limiting agreements cause unnecessary suffering.  Ruiz also believes that to find personal joy, one must get rid of socially imposed and fear-based agreements that can unconsciously influence the individual`s behaviour and thinking.  Another fundamental premise of the book suggests that much of the suffering is created and that most people have the ability to transform themselves and the negative thoughts they have about the situations in their lives.  The author identifies the sources of unhappiness in life and proposes four beneficial agreements that can be concluded with oneself to improve their general state of well-being. By pacting with these four most important chords, an individual is able to dramatically influence the amount of happiness he feels in his life, regardless of external circumstances.  The second agreement offers readers the opportunity to manage the hurtful treatments of others that they may experience in life.
She argues that it is important to have a strong self-concept and not to have to rely on the opinions of others to be satisfied and satisfied with their self-concept. This agreement also allows readers to understand the idea that each individual has a unique vision of the world that changes his or her own perception and that a person`s actions and beliefs are a projection of his or her personal reality.  Ruiz believes that anger, jealousy, envy and even sadness can subside or dissipate as soon as an individual stops taking things in person.  The Fourth Agreement allows readers to have a better understanding of the progress made in achieving their goals in life.