Compared to other agencies in the sample, hospitals identified victims who were younger, who had younger parents, who were black, and who lived in urban areas. There were no major differences between cases reported by hospitals and those reported by other agencies with respect to income, mode of medical payment, proportion of single-parent families, child's sex, or other demographic variables. Hospitals identified many more cases of physical abuse than did other agencies. The proportion of cases in this category alone exceeded the proportion of physical, sexual, and emotional abuse cases recognized by all other agencies. Hospitals failed to report to child protection agencies almost half the cases that met the study's definition of abuse. Discriminant analysis revealed that income, mother's role in the abuse, race, maternal employment, and sexual abuse distinguished reported from unreported cases. Disproportionate numbers of unreported cases were victims of emotional abuse and came from higher income families. In these cases, mothers were more often white and more often alleged to be responsible for the injuries. Methodological information is appended. 2 tables and 11 references. (Author abstract modified)