  We present model fits to spectral energy distributions in the optical and NIR
of >100 flat-spectrum radio quasars from the Parkes Half-Jansky Flat-spectrum
Sample. We find that approximately 40% of the sources have power-law SEDs,
while a similar number show evidence for two primary components: a blue power
law and optical synchrotron emission. The blue power law is similar to the
dominant component observed in the spectra of optically-selected QSOs. There is
strong evidence that the synchrotron component has a turnover in the UV-optical
rest frame of the spectrum. In the remaining sources it is likely that the
synchrotron peaks at longer wavelengths. This mixture of two components is
supported by optical polarisation measurements in a subgroup of the sources.
The sources with power law SEDs show evidence for an excess number of red power
law slopes compared to optically-selected quasars. There are additional
spectral components in some of the sources, such as dust and the underlying
galaxy, which have not been considered here.
