  We present imaging observations at 1.3 mm wavelength of Class I protostars in
the Taurus star forming region, obtained with the CARMA interferometer. Of an
initial sample of 10 objects, we detected and imaged millimeter wavelength
emission from 9. One of the 9 is resolved into two sources, and detailed
analysis of this binary protostellar system is deferred to a future paper. For
the remaining 8 objects, we use the CARMA data to determine the basic
morphology of the millimeter emission. Combining the millimeter data with 0.9
micron images of scattered light, Spitzer IRS spectra, and broadband SEDs (all
from the literature), we attempt to determine the structure of the
circumstellar material. We consider models including both circumstellar disks
and envelopes, and constrain the masses (and other structural parameters) of
each of these components. We show that the disk masses in our sample span a
range from <0.01 to >0.1 Msun. The disk masses for our sample are significantly
higher than for samples of more evolved Class II objects. Thus, Class I disk
masses probably provide a more accurate estimate of the initial mass budget for
star and planet formation. However, the disk masses determined here are lower
than required by theories of giant planet formation. The masses also appear too
low for gravitational instability, which could lead to high mass accretion
rates. Even in these Class I disks, substantial particle growth may have hidden
much of the disk mass in hard-to-see larger bodies.
