  We test the models of synchrotron emission presented in Part I of this series
(Lloyd & Petrosian, these proceedings) against the distributions and evolution
of GRB spectral parameters (particularly the low energy index, $\alpha$). With
knowledge of the $E_{p}$ distribution and the correlation between $\alpha$ and
$E_{p}$ presented in Part I, we show how to derive the expected distribution of
$\alpha$ from fits to optically thin synchrotron spectra, and compare this with
the observed distribution. We show that there is no difficulty explaining
bursts below the ``line of death'', $\alpha < -2/3$, and that these bursts
indicate that the spectrum of accelerated electrons must flatten or decline at
low energies. Bursts with low energy spectral indices that fall above this
limit are explained by the synchrotron self-absorption frequency entering the
lower end of the BATSE window. Finally, we discuss a variety of spectral
evolution behavior seen in GRBs and explain this behavior in the context of
synchrotron emission from internal shocks.
