The idea of less eligibility is that the public will not allow convicted felons to live at a level of luxury or privilege above the lowest classes in society. The paper considers the history of less eligibility stemming from the English Poor Laws and the writings of Jeremy Bentham, who is credited with being the author of the concept of the principle. Less eligibility, as applied to the prison system, became the instrument for managing changing class relations which arose in the eighteenth century and continued through most of the nineteenth century. Then an analysis of the principle is presented relative to sentencing discretion, deterrence, prison reform, the quality of prison life, convict labor, rehabilitation programs, jail practices, and post-release experiences. 1 figure and 53 references (Author abstract modified)