  We consider the nonequilibrium evolution of an O(N)-symmetric scalar quantum
field theory using a systematic two-particle irreducible 1/N-expansion to
next-to-leading order, which includes scattering and memory effects. The
corresponding ``full Kadanoff-Baym equations'' are solved numerically without
further approximations. This allows one to obtain a controlled nonperturbative
description of far-from-equilibrium dynamics and the late-time approach to
quantum thermal equilibrium. Employing in addition a first-order gradient
expansion for the Wigner transformed correlators we derive kinetic equations.
In contrast to standard descriptions based on loop expansions, our equations
remain valid for nonperturbatively large fluctuations. As an application, we
discuss the fluctuation dominated regime following parametric resonance in
quantum field theory.
