  We present methods to measure the beam polarizations and the luminosity of
$\gamma \gamma$ colliders at TeV energy scale.
  The beam polarizations of a $\gamma \gamma$ collider can easily be monitored
by comparing the numbers of events of the processes $\gamma \gamma$
$\rightarrow$ $\ell^+ \ell^-$ and $\gamma \gamma$ $\rightarrow$ $W^+ W^-$,
where $\ell$ means $e$ or $\mu$.
  The luminosity of a $\gamma \gamma$ collider is also measurable by the event
rate of $W$ boson pair productions and the light lepton pair productions.
