  We analyze new physics contributions to $e^+e^-\to W^+W^-$ at the TeV energy
scale, employing an effective field theory framework. A complete basis of
next-to-leading order operators in the standard model effective Lagrangian is
used, both for the nonlinear and the linear realization of the electroweak
sector. The elimination of redundant operators via equations-of-motion
constraints is discussed in detail. Polarized cross sections for $e^+e^-\to
W^+W^-$ (on-shell) are computed and the corrections to the standard model
results are given in an expansion for large $s/M^2_W$. The dominant relative
corrections grow with $s$ and can be fully expressed in terms of modified
gauge-fermion couplings. These corrections are interpreted in the context of
the Goldstone boson equivalence theorem. Explicit new physics models are
considered to illustrate the generation and the potential size of the
coefficients in the effective Lagrangian. Brief comments are made on the
production of $W^+W^-$ pairs at the LHC.
