Rates of substantiated maltreatment documented by the 1993 and 1998 Ontario Incidence Studies of Reported Child Abuse and Neglect doubled between 1993 and 1998. Although increasing public awareness and changes in investigation procedures appear to account for part of this change, the increase also reflects a significant shift in the types of maltreatment agencies are investigating and substantiating. Exposure to spousal violence has increased eightfold, and the proportion of neglect cases has more than doubled, whereas cases of sexual abuse are decreasing. The field requires a differentiated response to address the maltreatment-specific challenges underlying child welfare caseload increases in Canada.