Numerous changes have occurred since the first edition of this "Encyclopedia" (which was a CHOICE Outstanding Reference) published in 1995. These changes include the decrease of crack cocaine use and resurgence of heroin use; changes in laws dealing with drug use — on both the state and national levels; and new discoveries leading to a better understanding of how drugs work and what makes them addictive. More than 700 articles intended for the student and layperson cover the social, medical and political issues related to drugs and alcohol, as well as types of addiction.