  The ratio of neutral Higgs field vacuum expectation values, tan(beta), is one
of the most important 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 sqrts=500 GeV and
L=2000 fb-1 at a future linear collider (LC), we show that a very accurate
determination of tan(beta) will be possible for low and high tan(beta) values
by measuring the production rates of Higgs bosons and reconstructing Higgs
boson decays. In particular, based on a TESLA simulation, and assuming no other
light Higgs bosons and 100<=mA<=200 GeV, we find that the rate for the process
e+e- --> bbA --> bbbb provides a good determination of tan(beta) at high
tan(beta). In the MSSM Higgs sector, in the sample case of mA = 200 GeV, we
find that the rates for e+e- --> bbA+bbH --> bbbb and for e+e- --> HA --> bbbb
provide a good determination of tan(beta) at high and low tan(beta),
respectively. We also show that the direct measurement of the average total
widths of the H and A in e+e- --> HA --> bbbb events provides an excellent
determination of tan(beta) at large values. In addition, the charged Higgs
boson process e+e- --> H+H- --> tbtb has been studied. The sensitivity to
tan(beta) at the LHC obtained directly from heavy Higgs boson production is
briefly compared to the LC results.
