The study had three main objectives: (1) examine joint investigations at the local level by conducting a national survey of law enforcement and CPS agencies; (2) identify elements of effective joint investigations by studying innovative cooperative programs in selected localities; and (3) develop joint investigation program models to enhance existing programs. Surveys were sent to law enforcement and CPS agencies, and responses were received from 325 municipal police agencies, 179 county law enforcement agencies, and 239 CPS agencies. In addition to the surveys, case studies were conducted in seven counties (Texas, Indiana, Washington, Alabama, Maryland, and California). It was found that 80 percent of police agencies and 95 percent of sheriff departments conducted joint investigations with local CPS agencies. CPS agencies reported that 20 percent of child maltreatment allegations they investigated in fiscal year 1991 were joint investigations with law enforcement. Interagency agreements between law enforcement and CPS agencies typically contained provisions for notification and reporting responsibilities of team members, criteria for joint investigations, interviews within the investigation, and the geographic area served by the team. Survey findings and case studies were used to develop guidelines for three model joint investigation programs: model based on existing agency personnel and resources; model offering a multidisciplinary interview center to facilitate victim interviews; and model using a comprehensive child advocacy center for more effective joint investigations. Benefits of joint versus independent child abuse investigations are noted.