  We present high spatial resolution (< 0.3" = 40$ AU) Submillimeter Array
observations of the 865 micron continuum emission from the circumstellar disk
around the young star DoAr 25. Despite its bright millimeter emission, this
source exhibits only a comparatively small infrared excess and low accretion
rate, suggesting that the material and structural properties of the inner disk
may be in an advanced state of evolution. A simple model of the physical
conditions in the disk is derived from the submillimeter visibilities and the
complete spectral energy distribution using a Monte Carlo radiative transfer
code. For the standard assumption of a homogeneous grain size distribution at
all disk radii, the results indicate a shallow surface density profile, $\Sigma
\propto r^{-p}$ with p = 0.34, significantly less steep than a steady-state
accretion disk (p = 1) or the often adopted minimum mass solar nebula (p =
1.5). Even though the total mass of material is large (M_d = 0.10 M_sun), the
densities inferred in the inner disk for such a model may be too low to
facilitate any mode of planet formation. However, alternative models with
steeper density gradients (p = 1) can explain the observations equally well if
substantial grain growth in the planet formation region (r < 40 AU) has
occurred. We discuss these data in the context of such models with dust
properties that vary with radius and highlight their implications for
understanding disk evolution and the early stages of planet formation.
