  In most supersymmetric theories charginos, $\tilde{\chi}^\pm_{1,2}$, belong
to the class of the lightest supersymmetric particles. The chargino system can
be reconstructed completely in $e^+e^-$ collider experiments:
$e^+e^-\to\tilde{\chi}_i^+ \tilde{\chi}_j^- [i,j=1,2]$. By measuring the total
cross sections and the asymmetries with polarized beams, the chargino masses
and the gaugino-higgsino mixing angles of these states can be determined
accurately. If only the lightest charginos $\tilde{\chi}_1^\pm$ are
kinematically accessible in a first phase of the machine, transverse beam
polarization or the measurement of chargino polarization in the final state is
needed to determine the mixing angles. From these observables the fundamental
SUSY parameters can be derived: the SU(2) gaugino mass $M_2$, the modulus and
the cosine of the CP-violating phase of the higgsino mass parameter $\mu$, and
$\tan\beta = v_2/v_1$, the ratio of the vacuum expectation values of the two
neutral Higgs doublet fields. The remaining two-fold ambiguity of the phase can
be resolved by measuring the normal polarization of the charginos. Sum rules of
the cross sections can be exploited to investigate the closure of the
two-chargino system.
