Presents findings, for a five-year period from 2006 to 2010, on the characteristics of crime victimizations that went unreported to police, according to data from the National Crime Victimization Survey. The characteristics examined in this report include the type of crime, whether it involved a weapon or injury, the victim-offender relationship, and demographic characteristics of the victim. For each of the characteristics examined, the report also details victims’ rationale for not reporting to the police, including beliefs that the police would not or could not help, that the crime was not important enough to report, or fear of reprisal or getting the offender into trouble. The report also examines trends from 1994 to 2010 in the types of crime not reported to the police and the reasons victimizations went unreported.