The GEDI railgun program is a broadly based physics and engineering research and development effort for high-velocity, low-projectile mass railguns. A description of the facilities and some of the experiments is given. Areas of experimental investigation include (a) lexan and ceramic insulators, (b) plasma, hybrid and transitional armatures, (c) projectiles, (d) current pulse shape, and (e) bore shape. The objective is to achieve ablation-free acceleration to high velocity. Experiments have been performed on lexan insulator guns of 3.6 m length and on ceramic insulator guns of 0.9 m length. Experiments on the 3.6 m gun have demonstrated that armatures can be successfully formed from injected plasmas and have achieved velocities of 5.1 km/s. Experiments with ceramic insulator guns have successfully demonstrated acceleration of projectiles to velocities above 2 km/s without breakage of the ceramic. >