Section I of this article describes sources of U.S. adult parole data. Most of what is known about U.S. parolee characteristics comes from the Bureau of Justice Statistics (BJS), the statistical arm of the U.S. Department of Justice. Since the early 1980's, BJS has reported on the number of persons entering and exiting parole through its National Corrections Reporting Program. Section II discusses the early evolution of parole in the United States, as well as its use in modern sentencing practices. This section reviews the dramatic changes in parole release that resulted from the Nation's skepticism about the ability of prisons to rehabilitate. Section III describes the current parole population. It presents trend data on the growth of the parole population and what is known about parolees' crime, personal backgrounds, and court-ordered conditions. It also presents data on the average size of parole caseloads, offender contact requirements, and annual costs of supervision. Section IV describes the offender's needs as he/she transitions to the community, as well as the services that are available to meet these needs. This section also outlines the civil disabilities that apply to ex-convicts. Part Two of this article will appear in the Fall 2000 issue of "Perspectives." 1 figure and 4 tables