Almost one-fifth (19 percent) of the 12 to 30-year-olds admitted to one or more offenses in the last 12 months. Men (26 percent) were more likely to admit offending than women (11 percent). Those aged 14 to 21 were the most likely to be offenders. The average age when offending began was 13 1/2 for boys and 14 for girls. Half of those who said they had offended in the last year admitted just one or two offenses; but the most prolific 10 percent of offenders were responsible for nearly half of all the crimes reported; they represented 1 percent of the full sample. Type of offending varied by age. Among men, for example, fighting and criminal damage composed two-thirds of offenses among 12 to 13-year-olds, half of 14 to 15-year-olds' offenses, and less than 1 in 20 offenses committed by 26 to 30-year-olds. The proportion of men who admitted to property offenses stayed about the same until age 25; it declined in the late 20's, when offending involved mainly fraud (primarily tax evasion and expenses fraud) or workplace theft. Between 1992 and 1993 and 1998 and 1999, offending among boys aged 14-17 increased by 14 percentage points, but fell by 6 percentage points among men aged 18 to 25. There was little change for women overall; however, these figures conceal changes in specific offenses over time. Fighting increased among males, although it fell among females. Buying and selling stolen goods decreased, as did fraud among males. Three percent of all 12 to 30-year-olds (4 percent of men and 1 percent of women) reported they had been cautioned or taken to court in the last 12 months on at least one occasion. This was 12 percent of those who admitted offending and 18 percent of persistent offenders. The report concludes that the findings suggest the importance of strengthening family relationships between youth and their parents, reducing truancy and exclusion, encouraging drug education and treatment programs, promoting health education, and raising the awareness of youths and their families about the services and facilities available to them. 3 tables, 4 figures, and 1 references