This article examines how close the Spanish penitentiary system comes to fulfilling an ideal role for the prison in the system of punishment based on: (a) limitation of the use of imprisonment; (b) normalization of prison life; and (c) early reintegration into society of prisoners in the process of rehabilitation. On the basis of official reports and data of the years 1996-2003, it is first shown that although non-custodial punishments have produced a reduction in the use of imprisonment, this effect has been extensively compensated for by the increased period that prisoners have to serve before parole is granted. Second, although prison conditions have improved considerably since the 1990s, the system continues to suffer from some important shortcomings. Finally, the article compares the use of open prison and parole in the two administrations that manage Spanish prisons (the Catalan administration and the General Administration of the State) and explores the relationship between a policy based on rehabilitation and the effective duration of the sentence.