  It is widely stated that the ratio of neutral Higgs field vacuum expectation
values, $\tanb$, is one of the most difficult parameters to determine in either
the Minimal Supersymmetric Standard Model (MSSM) or a general type-II Two-Higgs
Doublet Model (2HDM). Assuming an energy and integrated luminosity of
$\rts=500\gev$ and $\call=2000\fbi$, we show that a very accurate determination
of $\tanb$ will often be possible using Higgs production rates and/or Higgs
decays. Based on a TESLA simulation, and assuming no other light Higgs bosons
and $100\leq m_A \leq 200\gev$, we find that the rate for the process $\epem\to
b\anti b A \to b\anti b b\anti b$ provides an excellent determination of
$\tanb$ at high $\tanb$. In the MSSM Higgs sector, the rate for $\epem\to
b\anti b A+ b\anti b H \to b\anti b b\anti b$ ($\epem\to HA \to b\anti b b\anti
b$) provides a good determination of $\tanb$ at high (low) $\tanb$,
respectively, at moderate $m_A$ values. We also show that direct measurement of
the average total width of the $H$ and $A$ in $\epem\to HA \to b\anti b b\anti
b$ events provides an excellent determination of $\tanb$ at large $\tanb$.
