  Detailed radial/vertical structure modeling of observations of disks around
Young Stellar Objects (YSOs) can provide information on the physical conditions
and on the characteristics of the gas and dust in their interiors. We describe
recent results of self-consistent modeling of spectral energy distributions,
optical and infrared images, and millimeter fluxes of YSOs. We discuss
observations and interpretations of the initial stages of planet formation,
including indications of dust growth and settling in disks around young stars.
We also discuss how the unprecedented resolution and sensitivity of ALMA may
help us study the interior of the innermost disks, a region unaccessible with
present day instrumentation, and witness the very first stages of planet
formation.
