Resolution of nearby giant HII regions (GHRs) into their stellar and nebular
constituents provides fundamental insights for interpreting more distant and
powerful starburst activity.  At a distance of 0.84 Mpc, M33 is the closest
galaxy which contains a large number of GHRs of differing metallicity and
luminosity.  As such, M33 provides the ideal laboratory for investigating the
degree to which metallicity and environment affect the stellar and nebular
properties of starbursting systems.  We have obtained HST/WFPC2 images of 6
GHRs in M33.  These multi-band images clearly resolve the underlying stellar
populations down to a linear scale of 0.4 pc.  Complementary groundbased
imaging at H-alpha, [SII], and other emission lines reveal disturbed
morphologies and strong excitation gradients in the ionized gas.  Photometric
analysis of the resolved stellar populations indicate a puzzling shortfall of
ionizing luminosity relative to the gaseous ionization.  What could be
providing the additional ionization?  We propose to address this
question by imaging the IR line emission and continua from these starburst
nebulae.  The many fine-structure emission lines in the IR spectrum
span a wide range of ionization energies, thereby providing well-resolved
diagnostics of the radiative and mechanical (shock) energetics at work in the
nebulae.  They are also not subject to extinction like those measured in the
visible. The distribution of continuum emission from the entrained dust grains
will further constrain the fraction of ionizing radiation that is absorbed and
thus removed from the ionization budget.  The combined dataset will be
unparalleled in its comprehensive and detailed coverage of GHRs, thereby
providing a solid foundation for diagnosing the composite stellar and nebular
emission from more distant galaxian starbursts.