Recent research on issues of comprehension, memory, and communication skills of children is evaluated within the context of courtroom testimony requirements. Reactions of various audiences, such as attorneys, judges, and jurors to the credibility of children are described. Procedures designed to reduce the traumatization of children who testify in court are assessed including their relevance to recent U.S. Supreme Court decisions that have responded to alternative ways of testifying by sexually abused children. Child and adolescent development is reviewed from a psychological perspective that focuses on brain development, perception, attention, cognition, psychosocial needs, and morality. Recommendations for judges, attorneys, and service delivery professionals who work with children who may be called on to testify are based on case law and social science data. The authors indicate that courts should provide the means necessary to allow children to communicate what they know, protect defendant's constitutional rights, apprehend and convict criminals, detect false accusations, and protect children from further injury and harm. Facts and details from actual cases involving child witnesses are presented. 362 references, 26 notes, and 9 tables