  We examine the prospects for determining $tan \beta$ from heavy Higgs scalar
production in the minimal supersymmetric standard model at a future $e^+ e^-$
collider. Our analysis is independent of assumptions of parameter unification,
and we consider general radiative corrections in the Higgs sector. Bounds are
presented for $\sqrt{s} = 500$ GeV and 1 TeV, several Higgs masses, a variety
of integrated luminosities and b-tagging efficiencies, and in scenarios with
and without supersymmetric decays of the Higgs bosons. We find stringent
constraints for $3 \alt tan \beta \alt 10$, and, for some scenarios, also
interesting bounds on high $tan \beta$ through $tbH^{\pm}$ production. These
bounds imply that simple Yukawa unifications may be confirmed or excluded.
Implications for soft scalar mass determination and top squark parameters are
also discussed.
