This study explored how the histories of young people entering residential treatment in New York State varied depending upon the age and gender of the residents. Specifically, we asked whether children who were admitted to residential treatment centers (RTCs) under 12 years of age had a different set of characteristics than young persons who were 12 years and older when admitted (and whether boys had different characteristics than girls). Three sets of characteristics were examined: history of maltreatment, history of behavioral problems, and history of mental health problems. One-fourth of the admissions in FY 2001 was randomly selected from a sample of 16 RTCs. A review of agency records provided the information to complete the standardized data collection instrument. The results revealed statistically significant patterns of associations by age and gender. As populations shift within agencies and across time, knowledge of the characteristics associated with various age and gender groups can be used to facilitate agency planning and training of staff members. (Contains 1 note and 3 tables.)