This study had two main objectives. The first was to assess the prevalence of DSM-IV borderline personality disorder and its constituent symptoms in a community sample of late-latency children. The second was to compare these rates to those found in a community sample of American adults. A birth cohort of 6,330 11-year-old children in Bristol, England, was interviewed concerning borderline psychopathology in 2002-2004. A community sample of 34,653 American adults was interviewed about borderline psychopathology in 2004-2005. Rates of chronic emptiness, physically self-damaging acts, and stormy relationships were very similar in both samples (<2% difference). However, a significantly higher percentage of children than adults reported being angry and moody. In contrast, a significantly higher percentage of adults than children reported being paranoid/dissociated, having a serious identity disturbance, being impulsive, and making frantic efforts to avoid abandonment. In addition, a significantly higher percentage of adults than children met DSM-IV criteria for BPD (5.9% vs. 3.2%). Statistically significant but clinically minor gender differences were also found between girls and boys as well as men and women. Taken together, the results of this study suggest that late-latency children are about half as likely as adults to meet DSM-IV criteria for BPD. They also suggest that gender does not play a defining role in symptom expression.