We investigated dispersal patterns of San Joaquin kit foxes (Vulpes macrotis mutica) on the Naval Petroleum Reserves, California. Of 209 juvenile kit foxes monitored during 1980–1996, 33% dispersed from their natal territory. Significantly more males (49.4%) than females (23.8%) dispersed, and dispersal peaked in July. Dispersing males tended to be heavier than philopatric males; philopatric females were significantly heavier than dispersing females. Expressed as a percentage of all juveniles monitored, annual dispersal ranged from 0% to 79% for males, 0% to 50% for females, and 0% to 52% for all foxes. Percentage of male dispersal was related weakly to mean annual litter size (r² = 0.27), and percentage of female dispersal was weakly and inversely related to annual indices of small-mammal abundance (r² = 0.46). Most (65.2%) dispersing juveniles died within ≤10 days of leaving their natal range. Survival tended to be higher for dispersing males than for philopatric males but was similar between dispersing and philopatric females. Sixty percent of all foxes that survived to breeding age reproduced except among dispersing females, none of which reproduced. Alloparental care did not account for sex-biased dispersal in kit foxes. Auxiliary adults were observed occasionally with mated pairs, but helping behavior was not observed. Dispersal patterns of kit foxes may be a function of innate sex-biased dispersal altered by physical and biological pressures.