  We study the prospects for probing the quark content of the photon using b
tagging at high energy electron-photon colliders. We find that heavy quark
tagging provides a sensitive and effective probe of the quark content of the
photon. Using a 500 GeV $e^+e^-$\ NLC in electron-photon mode, the cross
section for $eb_{\gamma}\rightarrow eb$\ can be measured to 10\% with b
tagging. This is sufficient to differentiate between the various photon
structure functions.
