The gamma-ray large area space telescope (GLAST) is a proposed next-generation high-energy gamma-ray telescope for studying emission from astrophysical sources in the 10 MeV to 300 GeV energy range. GLAST is currently under study as a NASA new mission concept in astrophysics. The primary scientific targets for the GLAST mission include active galactic nuclei, gamma-ray bursts, neutron stars, and the diffuse galactic and extragalactic high-energy radiation. GLAST relies on the unambiguous identification of incident gamma-rays by detection of the electron and positron that result from pair creation in a thin converter material. Measurement of the energy and direction of the electron- positron pair shower provides information about the energy and direction of the incident gamma-ray. The GLAST design utilizes modern solid-state particle detector technology and recently developed space-qualified computers. Because of the technical approach, the telescope design can be easily optimized to a range of sizes. For example, accommodation of GLAST within a Delta II size launch system results in an instrument with capabilities well beyond those of the highly successful EGRET currently operating on the Compton Observatory; namely, a broader energy range, larger effective area, wider field of view, and single-photon angular resolution 2 to 5 times more precise than EGRET's resolution. GLAST will have an effective area of 8000 cm2 above 300 MeV, a field of view of 2.6 sr, and single photon angular resolution (rms projected) of 0.3 degrees at 1 GeV, approaching 0.03 degrees above 20 GeV.