  We explore the capability of a 500 or 1000 GeV $e^+e^-$ linear collider to
measure anomalous quartic gauge boson couplings. In the framework of a
non-linear effective Lagrangian with a custodial $SU)2)$ symmetry, there are
only two next-to-leading order operators which contribute to quartic, but not
to two- and three- gauge boson interactions. The limits on the coefficients of
these operators from present and future $e^+e^-$ colliders are compared with
those available from other sources.
