Professionals who come in contact with children as a part of their occupation (e.g., teachers, police officers, doctors, childcare providers) are required by law in most States to notify child protective services agencies of suspected maltreatment. Thus, professionals are the most common source of maltreatment reports (57%). Sources other than professionals (including relatives, neighbors, and anonymous sources) account for the remaining 43% of reports.

From Juvenile Offenders and Victims: 2006 National Report

For more information on child abuse prevention, see the article "The National Children's Advocacy Center.