To prove the crime of street terrorism (Pen. Code, sec. 186.22, subd. (a)) and the gang enhancement (sec. 186.22, subd. (b)(1)), the testimony of a qualified gang expert is sufficient to support a finding as to the existence of a street gang, that appellant is a member of the gang, and that the offense was committed to aid the gang. CALCRIM 1400 adequately sets forth the elements of street terrorism and, with this instruction, it is not probable that a jury would convict on the basis of gang membership alone. Here, the experts eight years dealing with the target gang, including investigations and personal conversations with members, sufficed to establish the foundation for his testimony.