Several computer programs are available to help Army installations plan military training activities while ensuring environmental quality and protecting natural resources. One such system, the Geographic Resources Analysis Support System (GRASS), requires digital spatial information for developing area-specific databases. This information previously was available only on a limited basis. Today, many more digital spatial data sources have come into existence. Use of such sources, compared with generating new data, can usually save an installation a large amount of time and money. In addition, these sources ensure minimum standards for accuracy and quality. This report identifies digital data sources to help installations evaluate the feasibility of implementing systems such as GRASS. Included is a list of the following characteristics for each source: format, scale/resolution, coverage, media, costs, and a textual description. Keywords: Army facilities, Army training.