Until recently, law enforcement and policymakers had few hard data on the child victims of sexual abuse, offenders, and other characteristics of these crimes on which to base a response. The National Incident-Based Reporting System (NIBRS), capturing a wide range of information on each sexual assault incident reported to law enforcement, can provide such information. Two research bases were extracted from 1991 through 1996 NIBRS master files, one summarizing information for the 60,991 victims of sexual assault, and the second compiling information for the 57,762 victim-identified offenders. The findings indicated that 67 percent of sexual assaults are against juvenile victims. Juvenile victims of sexual assault were more likely to be male (18 percent) than were adult victims (4 percent). Juvenile victims were more likely to be victimized with others (20 percent) than were adults (4 percent). Nearly 5 of every 6 sexual assaults of young juveniles occurred in a residence, whereas crimes against older juveniles and adults were more likely to occur elsewhere. Adults were the offenders in 60 percent of sexual assaults of youth under age 12. Rarely were the offenders strangers to the victims. Sexual assaults of children under 6 years were the least likely of all such crimes to result in arrest or be otherwise cleared. (The report concludes with a list of NIBRS definitions of forcible sex offenses. An appendix discusses difficulties in data analysis when the victim's perception of the offender's age may be reported as a point estimate or as a range.) (KB)