  The model of Natural Inflation is examined in light of recent 3-year data
from the Wilkinson Microwave Anisotropy Probe and shown to provide a good fit.
The inflaton potential is naturally flat due to shift symmetries, and in the
simplest version takes the form $V(\phi) = \Lambda^4 [1 \pm \cos(N\phi/f)]$.
The model agrees with WMAP3 measurements as long as $f > 0.7 m_{Pl}$ (where
$m_{Pl} = 1.22 \times 10^{19}$GeV) and $\Lambda \sim m_{GUT}$. The running of
the scalar spectral index is shown to be small -- an order of magnitude below
the sensitivity of WMAP3. The location of the field in the potential when
perturbations on observable scales are produced is examined; for $f > 5
m_{Pl}$, the relevant part of the potential is indistinguishable from a
quadratic, yet has the advantage that the required flatness is well-motivated.
Depending on the value of $f$, the model falls into the large field ($f \ge 1.5
m_{Pl}$) or small field ($f < 1.5 m_{Pl}$) classification scheme that has been
applied to inflation models. Natural inflation provides a good fit to WMAP3
data.
