  Gamma ray burst afterglows can be identified in single epoch observations
using three or more optical filters. This method relies on color measurements
to distinguish the power law spectrum of an afterglow from the curved spectra
of stars. Observations in a fourth filter will further distinguish between
afterglows and most galaxies up to redshifts z ~ 1. Many afterglows can also be
identified with fewer filters using ultraviolet excess, infrared excess, or
Lyman break techniques. By allowing faster identification of gamma ray burst
afterglows, these color methods will increase the fraction of bursts for which
optical spectroscopy and other narrow-field observations can be obtained.
Because quasar colors can match those of afterglows, the maximum error box size
where an unambiguous identification can be expected is set by the flux limit of
the afterglow search and the quasar number-flux relation. For currently typical
error boxes (10 -- 100 square arcminutes), little contamination is expected at
magnitudes R < 21.5 +- 0.5. Archival data demonstrates that the afterglow of
GRB 000301C could have been identified using this method. In addition to
finding gamma ray burst counterparts, this method will have applications in
``orphan afterglow'' searches used to constrain gamma ray burst collimation.
