State-by-state guide:

Missouri

Mo. Rev. Stat. § 211.171(6) (1998); Mo. Juv. Ct. R. 117.02 (1999): In general, the members of the public are excluded from hearings except persons who have a direct interest in the case or the work of the court. Members of the public may also be admitted in cases where the child is accused of conduct which, if committed by an adult, would constitute a felony.

Mo. Rev. Stat. § 211.321 (1997); Mo. Juv. Ct. R. 122.02 (1999): Court records cannot be disclosed, except by court order to persons having a legitimate interest. If a child is charged with an offense which, if committed by an adult, would be a class A felony under the criminal code of Missouri, or capital murder, first degree murder, or second degree murder, the records may be open. Moreover, after a child has been adjudicated delinquent for an offense which would be a felony if committed by an adult, the records are to be open to the public to the same extent that records of adult criminal proceedings are open to the public. Furthermore, a juvenile officer may make public information concerning a juvenile’s offense, the substance of the petition, the status of proceedings in the juvenile court and any other information which does not specifically identify the child or the child’s family. In addition, police records of children are to be kept separate from the records of persons 17 years of age or over and shall not be open to inspection or their contents disclosed, except by order of the court. However, when a juvenile is charged with serous offense, this provision does not apply. Finally, after a child’s 17th birthday, if the court finds that it is in the best interest of the child, the court may destroy all social histories, records, and information, other than the official court file, and may enter an order to seal the official court file.