Self-interacting scalar fields coupled to matter, known as chameleon fields, can explain the accelerating expansion of the universe while evading current fifth force constraints. The GammeV Experiment, in its current configuration, is a search for cosmologically interesting chameleons that couple to photons as well as to matter. Chameleon particles generated through electromagnetic interactions, in a closed chamber containing a magnetic field, will remain confined to that chamber due to their matter interactions. These particles will gradually decay to photons, producing an "afterglow" effect which is a unique signature of photon-coupled chameleons. I will discuss the prospects for constraining such chameleon theories using GammeV.