The research was conducted in sites in South Norwood, Liverpool, Nottingham, and Sunderland. Two sites, Nottingham and Sunderland, were included in the same research 2 years earlier. This makes it possible to track changes in arrestees' drug use in these jurisdictions between 1997 and 1999. Sixty-nine percent of arrestees tested positive for at least one drug (excluding alcohol); 29 percent tested positive for opiates (including heroin), and 20 percent tested positive for cocaine (including crack). Between 1997 and 1999, drug use among arrestees increased. In Nottingham, there was an increase in heroin and crack/cocaine use, and in Sunderland there was a shift from alcohol to illegal drugs. Users of both heroin and crack/cocaine were five times more likely to report committing robbery and four times more likely to report shoplifting than arrestees who did not use these drugs. There was a small subgroup (9 percent) of especially prolific property offenders with costly drug habits. These arrestees admitted committing an average of at least 20 offenses a month over the last year while using heroin or crack/cocaine. They were responsible for 52 percent of all offenses reported by the full group of arrestees. One-third of all arrestees said they were dependent on at least one drug (excluding alcohol and tobacco) at the time of the interview. In Nottingham the proportion dependent on heroin increased from 12 percent to 23 percent between 1997 and 1999. Between 1997 and 1999, the availability of crack/cocaine and heroin in Nottingham increased significantly. 3 figures, 1 table, and 1 reference