New high-resolution measurements of the O-2 photoabsorption cross section in the 1147-1155 Angstrom region are presented. The observation of three previously-unreported narrow lines in a band near 1148 Angstrom has enabled unambiguous assignment of the band to a (1) Pi(u)<--X(3) Sigma(g)(-) transition which gains strength through a spin-orbit interaction with the upper state of a (3) Pi(u)<--X(g)(3-) transition appearing at 1153 Angstrom. Other lines in the 1148 Angstrom band are broadened by predissociation through a heterogeneous interaction with a nearly energetically coincident (1) Delta(u) level. The states, labelled h (1) Pi(u), F-3 Pi(u), and i(1) Delta(u), are predominantly of 4p lambda Rydberg molecular orbital configurations although there are indications that the Pi(u) states interact strongly with valence states of the same symmetry.