Globally, over 1 million children in conflict with the law are in detention, yet little research, particularly from Africa, has addressed their experiences of incarceration. Between September 2009 and February 2010, 246 prisoners, 30 prison officers, and 46 key informants from six prisons were interviewed as a part of a mixed-method study examining human rights conditions and HIV and tuberculosis (TB) prevention, treatment, and care in Zambia. Nineteen male and four female “juvenile” (ages eight to 18) prisoners participated in the study and completed a short quantitative survey and a longer, in-depth interview. Despite specific provision under international law that children should be detained only as a last resort, for the shortest appropriate time and be held separately from adults, we found that juvenile detainees in Zambia are routinely incarcerated for extended pre-trial periods, denied basic health care, imprisoned with adults, and face significant risk of contracting HIV and TB. Attention both to juveniles’ health needs, and to the criminal justice system failures that keep children incarcerated in adult facilities for extended periods, is necessary in order to improve health outcomes for children in conflict with the law in Zambia.