Dutch prison policy since World War II has been dominated by the rehabilitative ideal, but institutions housing dangerous and problem inmates are custodially-oriented. The custodial institutions strictly regulate inmate-staff relations, maintain tight inmate discipline, and limit inmates' freedom. Treatment-oriented institutions, on the other hand, focus on inmates' problems and needs, frequent informal contacts between staff and inmates, and inmate freedom within the institution. Using recidivism as the criterion, however, Dutch research has found that treatment-oriented institutions do not have a greater rehabilitative effect than custodially-oriented institutions, controlling for inmate background characteristics. Given this finding, official penal policy has lowered the expectation of rehabilitation and given priority to the humane execution of the sentence while minimizing the negative impacts of imprisonment and offering programmatic opportunities for inmates to improve their abilities to live responsibly upon release. Recent studies have shown a relationship between the characteristics of a prison and the characteristics of inmate subcultures. Rigid prison regimes tend to foster violence, disorder, and drug use among inmates. Research is underway to explore this connection further. 40 references.