  We study gauge extensions of the MSSM that contain non-decoupling D-terms,
which contribute to the Higgs boson mass. These models naturally maintain gauge
coupling unification and raise the Higgs mass without fine-tuning. Unification
constrains the structure of the gauge extensions, limiting the Higgs mass in
these models to roughly less than 150 GeV. The D-terms contribute to the Higgs
mass only if the extended gauge symmetry is broken at energies of a few TeV,
leading to new heavy gauge bosons in this mass range.
