The NCCD study focused primarily on the number and type of inmates in San Francisco jails. Study goals were to project the need for additional jail space over the next 20 years, identify key criminal justice policies and demographic factors that drive the 20-year projections, examine the extent to which alternatives to incarceration are being fully utilized, describe the handling of inebriated and mentally ill inmates, and assess the medical care system within jails. Study findings revealed that many individuals were jailed for relatively minor offenses and for brief periods of time. In particular, inmates charged with drug offenses and nontraffic warrants taxed jail population levels. It was also found that many inmates were caught in a nexus of repetitive minor law violations, alcohol and drug abuse, mental health problems, and homelessness. Using an offense-specific and demographically-sensitive inmate population forecasting model, it was determined that the average San Francisco jail population will gradually decline after 1990 if current criminal justice policies remain relatively stable. San Francisco already uses such alternatives to incarceration as citation release, county parole, and work furlough, but the importance of continued planning for alternatives to incarceration is stressed. Considerable improvements are needed in the handling of mentally ill and inebriated inmates, and it is recommended that the Sheriff's Department establish a civil detoxification program instead of housing inebriates in jail. Appendixes contain supplemental information on inmate flow, female inmates, women with children in correctional facilities, and the San Francisco Sheriff's Department Community Services Program. Tables and figures.