Depression is a serious illness, not a harmless part of life. It is a complex disorder with a variety of causes, including genetic, chemical, physical, and sociological. It is also influenced by behavior patterns learned in the family and by cognitive distortions. Depression affects thousands of people in the United States. It is always troubling, but for some people it can be disabling. Depression is more than just sadness or “the blues”; it can impact nearly every aspect of a person’s life. People who suffer from it may experience despair and worthlessness, feelings that can greatly influence both personal and professional relationships. In this handout, many of the factors that can cause depression are described, and strategies for preventing depression are explored.