  We present measurements of the branching fraction, the polarization
parameters and CP-violating asymmetries in B0 -> D*+ D*- decays using a 140/fb
data sample collected at the Upsilon(4S) resonance with the Belle detector at
the KEKB energy-asymmetric e+e- collider. We obtain B(B0 -> D*+ D*-) = [0.81 +-
0.08(stat) +- 0.11(syst)] x 10^{-3}, R\perp = 0.19 +- 0.08(stat) +- 0.01(syst),
R0 = 0.57 +- 0.08(stat) +- 0.02(syst), S = -0.75 +- 0.56(stat) +- 0.12(syst)
and A = -0.26 +- 0.26(stat) +- 0.06(syst). Consistency with Standard Model
expectations is also discussed.
