Observations of the spectral energy distributions (SEDs) and
 higher resolution spectra of circumstellar disks will be taken to
 investigate the physical properties of the disks.  The principal
 goals of the proposal are:

 1. To determine if current theories of disk structure and heating
    properly describe the spectral energy distributions between 5
    and 200 microns.

 2. To search for evolutionary changes in the disk properties
    brought about by the formation of planetary systems, for
    example, and the dissipation of the disks.

 3. To resolve five outstanding questions about disk properties
    which can only be assessed through high resolution observations:
    a. how are the disks heated,
    b. are the vertical temperature gradients in the disks positive
       (heating from above) or negative (heating from within by
       accretion),
    c. what are the sizes of the disks,
    d. what are the far infrared optical depths of the disks, and
    e. are there gaps in the disk structure which can be identified
       through the SEDs?