Psychologists are health professionals with training and expertise in human behavior and psychological health. Psychologists are not medical doctors, but they hold a doctor of psychology (PsyD degree) or doctor of philosophy (PhD degree) in clinical psychology, counseling, or school psychology.

Psychologists evaluate and treat people who have mental health problems, such as depression. Psychologists also provide counseling and other mental health services. In most states, psychologists do not prescribe medicine. But many states are reviewing prescription-writing privileges for psychologists, and regulations may change. Some psychologists practicing in New Mexico, Louisiana, the territory of Guam, the U.S. military, Indian Health Services, and other departments of the federal government have prescription privileges.

Psychologists are licensed in the state in which they practice.