This chapter focuses on anxiety disorders and argues that the anxiety disorders not only because they are among the most prevalent mental disorders, but also because many psychotherapy scholars have posited that a deeper understanding of them would shed light on most other mental disorders. Anxiety and fear are intimately involved in various forms of escape from, or avoidance of, potential danger. Anxiety disorders—according to neuroscientist Joseph LeDoux—involve a loss of cortical control of our evolutionarily adaptive fear system. From a behavioral perspective: Anxiety is the primary learning problem in psychopathology. The chapter reviews research suggesting that not only the different anxiety disorders but even other categories of mental disorders share a common genetic basis. Essential to attachment theory and psychodynamic theories of psychopathology is the fundamental role that anxiety plays in influencing behavior, thinking, and feeling. "