  We present the final results of the CP-PACS calculation of the light hadron
spectrum and quark masses with two flavors of dynamical quarks. Simulations are
made with a renormalization-group improved gauge action and a mean-field
improved clover quark action for sea quark masses corresponding to $m_{\rm
PS}/m_{\rm V} \approx 0.8$--0.6 and the lattice spacing $a=0.22$--0.11 fm. For
the meson spectrum in the continuum limit a clearly improved agreement with
experiment is observed compared to the quenched case, demonstrating the
importance of sea quark effects. For light quark masses we obtain
$m_{ud}^{\bar{MS}}(2GeV)=3.44^{+0.14}_{-0.22}$ MeV and
$m_s^{\bar{MS}}(2GeV)=88^{+4}_{-6}$ MeV ($K$-input) and
$m_s^{\bar{MS}}(2GeV)=90^{+5}_{-11}$ MeV ($\phi$-input), which are reduced by
about 25% compared to the values in quenched QCD.
