On this record, although the court failed to give the standard reasonable doubt instruction, such that federal constitutional error occurred, upon reviewing the entire record, the court found the error to be harmless. Appellant was charged with murder and participation in a criminal street gang. When instructing the jurors, the court failed to include the reasonable doubt instruction. As to the murder charge, the court instructed the jury that in order to find defendant guilty of that crime or a lesser included offense, it must find that the prosecution had proven each of the required elements beyond a reasonable doubt. With the participation in a criminal street gang offense, the court failed to indicate that each element must be proved beyond a reasonable doubt. The jury found appellant guilty of the lesser included charge of voluntary manslaughter and guilty of the gang offense. The Court of Appeal’s decision was affirmed in part and reversed in part. As to the murder charge, the court found that the omission of the reasonable doubt instruction did not constitute federal constitutional error because the trial court repeatedly referred to the prosecution’s burden of proving guilt beyond a reasonable doubt when instructing on the murder charge and its lesser included offenses, clearly connecting the requisite standard of proof to those offenses. As to the gang offense, the omission constituted federal constitutional error because the court’s instructions did not otherwise cover the requirement that the prosecution prove appellant’s guilt of the offense beyond a reasonable doubt. Resolving a conflict in the Courts of Appeal, the court concluded that the omission of the standard reasonable doubt instruction in violation of federal constitutional principles is subject to harmless error review and provided guidance on this issue. Here, the error was harmless. There was no reasonable possibility that the jury believed a lesser standard of proof applied to the gang offense. The trial court’s failure to define reasonable doubt constituted an error under state law but it was harmless.