  We discuss in detail top quark polarization in above-threshold (t \bar
t)-production at a polarized linear e^+ e^- collider. We pay particular
attention to the minimization and maximization of the polarization of the top
quark by tuning the longitudinal polarization of the e^+ and e^- beams. The
polarization of the top quark is calculated in full next-to-leading order QCD.
We also discuss the beam polarization dependence of the longitudinal spin-spin
correlations of the top and antitop quark spins.
