  The most interesting theoretical features of W-pair production in e+e-
collisions are reviewed. Based on an analysis of on-shell W-pairs, it is shown
that the mere inclusion of leading $O(\alpha)$ corrections--such as
initial-state radiation, effects from the universal quantities $\Delta\alpha$
and $\Delta r$, and the Coulomb singularity--cannot be expected to approximate
the $O(\alpha)$-corrected cross-section of $e^+e^-\to W^+W^-\to 4f$ to better
than 1-2% for LEP2 energies. The importance of the gauge-invariance problem,
arising from the introduction of finite decay widths, is discussed. The
simplest consistent method to include $O(\alpha)$ corrections at least to the
doubly resonant contributions, viz. a pole expansion around the double
resonance, is also briefly described.
