This project was designed to evaluate the use of a drug detection instrument, the ion mobility spectrometer (IMS), and to integrate its use into an ongoing pretrial diversion program for nonviolent, first-time, drug-abusing offenders. The Pretrial Diversion Program in Orleans Parish, Louisiana, targeted offenders with limited arrest histories of nonviolent felony or misdemeanor violations. The majority of eligible participants were violators of simple drug possession statutes, primarily crack/cocaine or marijuana. Persons charged with drug distribution offenses were not eligible. In order to qualify for diversion, persons had to admit guilt regarding the acts for which they were arrested. The program was entirely voluntary. One of the unique aspects of this program was its aggressive use of drug testing, including urinalysis and hair analysis. This project evaluated the ability of the IMS to provide complete drug profile information to supervising agencies and assessed its usefulness to field staff engaged in drug monitoring duties. The project was based on the premise that enhanced information on offenders diverted into this program could create or improve several key aspects of program operation, such as client assessment, monitoring of compliance and progress, dispositional decision-making, client motivation, and staff morale. The study was designed to integrate the IMS into the normal operation of the New Orleans Pretrial Diversion Program with as little modification of existing treatment and supervision protocols as possible. Each client in the diversion program underwent an intensive intake assessment including an intake radioimmunoassay (RIA) hair assay and an additional RIA hair assay every 60 days. Each client was urine-tested at intake and assigned to a random test pool. The modified protocol for the project added an IMS-based scan or a hair specimen, skin wipe, and ten-second vacuum scan of clothing, hands, and axillae at intake. At each subsequent visit each client had a repeat IMS scan utilizing a skin swab and a scan of clothing or body area. Variables include self-reported cocaine use, self-reported marijuana use, IMS date, urinalysis date, hair assay results, urinalysis results, IMS detection, nicotine use, maximum amplitude, delta, cumulative amplitude, number of detections, whether the IMS showed a positive result, and the age, sex, and race of the client.