The practice of incarceration has a long history and is utilized worldwide for numerous purposes ranging from public safety, detaining individuals for the purposes of judicial processes, punishment for illegal behavior, deterrence from future illegal behavior, and political leverage. In the first decade of the 21st century, the United States became the world’s leading incarcerator in the making. Consequently, this entry focuses only on the effects of incarceration in the United States during those five decades, an overview of which shows how the effects of incarceration extend well beyond those on an individual offender.