A new assignment of the vibrational structure of the Huggins band of ozone is given. The assignment is consistent with the symmetry requirements on changes in the asymmetric stretching (upsilon(3)) quantum number and with data on the differences in the location of vibronic bands between O-16(3) and O-18(3). Based on the reassignment of the spectrum, new values for the vibrational constants for O-16(3) and O-18(3) in the excited electronic state responsible for the Huggins system are calculated. The reassignment of the Huggins system provides a simple explanation for several otherwise puzzling observations concerning the spectrum, and suggests that the Huggins and Hartley band systems arise