Cortisol regulation was investigated in a sample of school-aged maltreated (n =175) and demographically comparable low-income nonmaltreated (n = 209) children inthe context of a day camp research program. Overall group differences between maltreated andnonmaltreated children were not found for average morning or average afternoon cortisol levels.However, significant variations were found that were based on the subtypes of maltreatment thatthe children had experienced. Maltreated children who had been both physically and sexuallyabused (as well as neglected or emotionally maltreated) exhibited substantial elevations inmorning cortisol levels; children who had high (>1 SD) cortisol levels in both themorning and afternoon were also overrepresented in the multiple abuse group. Developmentaltiming of maltreatment did not account for these group differences, whereas the severity of sexualabuse was implicated. In contrast to the multiple abuse group, a subgroup of physically abusedchildren showed evidence of a trend toward lower morning cortisol relative to nonmaltreatedchildren with a significantly smaller decrease in cortisol levels from morning to afternoon. Thefindings are discussed in terms of the diversity of atypical cortisol regulation patterns that areexhibited among maltreated children.