Many of the substances discussed in this book have both legal and illicit use. Alcohol is enjoyed in moderation at appropriate times by many people. The set and the setting associated with substance use constitute important elements in determining whether the substance is enhancing or destructive. Mood-altering substances (with the notable exception of caffeine) do not generally have a place at work. Intoxication is responsible for the majority of accidents and fatalities that occur on the job in the U.S. There are a number of substance abuse prevention and detection programs concerned with the workplace.