Evidence is presented for territorial behavior in a burrowing wolf spider, Geolycosa xera archboldi McCrone (Araneae, Lycosidae). These spiders live in burrows in the scrub habitats of central Florida, USA. Mean nearest-neighbor distances repeatedly approximate 30 cm. The constancy of this mean indicates that social spacing may be occurring. A test for perceptual range showed that G. xera can respond to potential prey at distances greater than 30 cm, indicating that the 30-cm nearest-neighbor distance does not represent a distance within which larger neighboring burrow-holders treat smaller neighboring conspecifics as food. Dyadic encounters in field enclosures showed that the distance at which neighbors would not be tolerated was within the observed mean nearest-neighbor distance. In these experimental tests for territorial behavior, smaller dyad members lost burrows significantly more often than larger dyad members.