  We present multi-color light-curves of the optical afterglow of GRB 000926.
Beginning ~1.5 days after the burst, the light-curves of this GRB steepen
measurably. The existence of such achromatic breaks are usually taken to be an
important observational signature that the ejecta are not expanding
isotropically, but rather have a collimated jet-like geometry. If we interpret
the data in this context, we derive an opening angle of 5 degrees, which
reduces the energy release compared to an isotropic model by a factor of ~275,
to 1.7 x 10^51 erg. To fit the data with a simple jet model requires extinction
along the line of sight. The derived A_V is in the range 0.11 - 0.82 mag,
depending on the adopted extinction law and whether the electrons giving rise
to the optical emission are undergoing synchrotron cooling or not. Since this
is in excess of the expected extinction from our Galaxy, we attribute this to
the GRB host. We note that this extinction is typical of a galactic disk, and
therefore the event likely took place in the disk of its host.
