  Assuming the exchange of antiferromagnetic spin fluctuations as the Cooper
pairing mechanism we calculate the doping dependence of the resonance peak seen
in inelastic neutron scattering and the magnetic coherence effect. Most
importantly, we find that the resonance peak in the magnetic susceptibility,
${Im}\chi({\bf q},\omega)$, appears {\it only} in the superconducting state,
that it scales with $T_c$, and that magnetic coherence is a result of a d-wave
order parameter. We further analyze the structure of ${Im}\chi$ below $T_c$,
the position of the peak at $\omega_{res}$ and the consequences for
photoemission, tunneling spectroscopy and the optical conductivity.
