This issue has taken on added significance as the number of child maltreatment reports continues to rise, whereas the percentage of those being substantiated declines. Regression analyses revealed that reports from professionals were substantiated at a significantly higher rate than reports from nonprofessionals for all types of maltreatment. These analyses further revealed that part of the effect of source of report was due to differences between professional and nonprofessional reports in the types of actions taken after the report was received. The most important predictors of substantiation, after source of report, were the variables that reflected the case investigatory process. The data also showed that background characteristics, such as the child's ethnicity or the number of children in the household, had some impact on the outcome of the investigation and that this varied as a function of the type of maltreatment. (Publisher abstract)