Beattie delves into the core of codependency, explaining that it's not just about being overly dependent on others but also about attempting to control them and their feelings. She emphasizes that codependents often neglect their own needs while focusing excessively on pleasing others, leading to feelings of resentment, anxiety, and emptiness. The book provides clear examples and relatable scenarios to help readers identify if they exhibit codependent tendencies.

A central theme of the book is the concept of "detachment with love." Beattie explains that true love requires respecting others' boundaries and allowing them to experience the consequences of their own choices. This means letting go of the need to fix, control, or rescue others, and instead focusing on personal growth and well-being. The book provides practical steps on how to establish healthy boundaries and communicate assertively.

"Codependent No More" stresses the importance of taking responsibility for one's own happiness and well-being. Beattie encourages readers to identify their own needs and desires, and to develop self-care practices that nurture their physical, emotional, and spiritual health. She emphasizes that by prioritizing self-care, individuals can break free from the cycle of codependency and build healthier, more fulfilling relationships.