The format of the manual has not changed—it is divided into chapters according to "types" of medications (e.g., chapter 3, "Antidepressants," chapter 4, "Antipsychotic Drugs," etc.). In this edition, there is much more information on selective serotonin reuptake inhibitors (SSRIs), which reflects our prescribing practice. Chapter 3, "Antidepressants," has an expanded section on SSRIs, and it includes a new table, "Inhibition of Cytochrome P-450 Isoenzymes by Antidepressants." This table is useful in helping the reader understand different SSRI-drug interactions (e.g., SSRIs increase the plasma level of some medications). Although the manual is divided into types of medications, there is a suborganization by DSM-IV diagnoses. Thus, one might look at chapter 6, "Anti-Anxiety Agents," for medications to treat anxiety disorders. In this chapter one would find information on the classes of antianxiety medications—benzodiazepines, barbiturates, etc. Also in this chapter, however, is a thorough section describing SSRIs as anxiolytic agents, with reference to chapter 3 for details concerning dosing, etc. Chapter 9, "Combination and Adjunctive Treatments," has been updated and expanded to reflect the increased use of SSRIs and anticonvulsant medications for psychiatric disorders.