  We investigate the band structure of BaBiO$_{3}$, an insulating parent
compound of doped high-$T_{c}$ superconductors, using \emph{in situ}
angle-resolved photoemission spectroscopy on thin films. The data compare
favorably overall with density functional theory calculations within the local
density approximation, demonstrating that electron correlations are weak. The
bands exhibit Brillouin zone folding consistent with known BiO$_{6}$ breathing
distortions. Though the distortions are often thought to coincide with
Bi$^{3+}$/Bi$^{5+}$ charge ordering, core level spectra show that bismuth is
monovalent. We further demonstrate that the bands closest to the Fermi level
are primarily oxygen derived, while the bismuth $6s$ states mostly contribute
to dispersive bands at deeper binding energy. The results support a model of
Bi-O charge transfer in which hole pairs are localized on combinations of the O
$2p$ orbitals.
