The PPN was established by the California Department of Corrections and the Department of Alcohol and Drug Programs in fiscal year 1991-92. PPN has several treatment networks located throughout the State. Each network provides one or more types of treatment, which include residential, outpatient, and drug detoxification treatment. parolees are eligible for up to 180 days of treatment. These services are provided through public and private vendors, which work under contract with county drug program officers. A total of 361 PPN participants were involved in the evaluation conducted from December 1994 to October 1995. Data show that over half of the PPN participants received only outpatient services compared to residential treatment only (31 percent) or a combination of both types of services (16.1 percent). The evaluation found that the odds of returning to prison during a 1-year follow-up were less for parolees with substance abuse problems who participated in PPN compared with those parolees who abused substances and did not participate in PPN. There was a 28-percent reduction in the odds of PPN participants being returned to prison. Other statistically significant predictors of return to prison were being under 30 years of age at first admission to a correctional institution, prior returns to prison, and involvement in property-related commitment offenses. Also, PPN participants who were returned to prison remained on parole for a longer period of time before the offense that occasioned their return to prison. A difference of nearly 2 months was statistically significant at a 95-percent confidence level. Among the PPN participants, those who stayed in PPN less than 3 months were over 6 times more likely to return to prison; those who had problems with cocaine, those less than 30 years old when admitted to prison, and those who were unemployed had higher odds of being returned to prison. 11 tables