  A direct measurement of the trilinear $WW\gamma$ and $WWZ$ couplings is
possible in the pair production of electroweak bosons at $e^+e^-$ and hadron
colliders. This talk addresses some of the theoretical issues: the
parameterization of ``anomalous couplings'' in terms of form factors and
effective Lagrangians, the complementary information which can be obtained in
$e^+e^-$ vs. hadron collider experiments, and a novel way to implement finite
$W$-width effects in a gauge invariant manner.
