background observed by the EGRET experiment which will be resolved as individual sources, such as blazars. If a large fraction of this background is resolved, the remaining extragalactic signal could potentially contain identifiable signatures of dark matter annihilations [@egdiffuse].

The telescopes potentially capable of detecting gamma rays from dark matter annihilations in the near future include the satellite-based experiment GLAST [@glast], and a number ground based Atmospheric Cerenkov Telescopes, including HESS, MAGIC and VERITAS. The roles played by each of these two classes of experiments in the search for dark matter are quite different. GLAST will continuously observe a large fraction of the sky, but with an effective area far smaller than possessed by ground based telescopes. Ground based telescopes, in contrast, study the emission from a small angular field, but with far greater exposure. Furthermore, while ground based telescopes can only study gamma rays with energy greater than $\sim$100 GeV, GLAST will be able to directly study gamma rays with energies over the range of 100 MeV to 300 GeV.

As a result of the different energy ranges accessible by these experiments, searches for dark matter particles lighter than a few hundred GeV are most promising with GLAST, while 