Findings confirmed study hypotheses that girls were more likely to have histories of sexual abuse and running away; older young persons were more likely to have histories of substance abuse, running away, and juvenile delinquency; and younger persons were more likely to have histories of suicidal actions, psychiatric hospitalizations, and psychotropic medication. Age by gender analyses also revealed distinct characteristics, such as older girls had histories of running away; younger girls experienced more sexual abuse and had histories of psychiatric hospitalizations. Older boys entered with histories of substance abuse and juvenile delinquency; and younger boys entered with histories of fire-setting, suicidal actions, psychiatric hospitalizations and psychotropic medication. The findings are consistent with prior research, and extend prior research in documenting the subgroups of young people most likely to enter residential treatment with specific problems with many avenues suggested in improving programs and practices. This study was conceived in order to build on earlier findings and the need to refine the understanding of the nature of the behavioral and mental health problems in the residential treatment centers (RTCs). It examined the extent to which age and gender of the residents were associated with the type of problems that they had experienced before placement. The study sample was comprised of young persons admitted to 16 New York State RTC agencies. Three sets of characteristics were examined: history of maltreatment, history of behavioral problems, and history of mental health problems. Tables, references