We studied the spatial organization of dusky-footed woodrats (Neotoma fuscipes) in mixed-conifer forest of the northern Sierra Nevada, California, by radiotracking 63 adult woodrats at 2 study sites during May–October 2004–2006. Estimates of home-range and core-area size differed between study sites, but they were within the range reported elsewhere; variability in home-range size was explained in part by density. Home ranges of woodrats overlapped those of multiple neighboring woodrats, both same sex and opposite sex, suggesting that foraging areas were shared. However, core areas showed little overlap between same-sex neighbors. Woodrats occupied multiple houses and frequently moved among them, and sharing of houses (either simultaneously or nonsimultaneously) with neighboring woodrats was common but occurred mostly between male–female pairs. Females typically shared their core area and houses with 1 male, whereas males shared core areas and houses with multiple females; further, males moved more than females. Our results suggest that dusky-footed woodrats are semiterritorial, maintaining near-exclusive use of their core area and houses against same-sex conspecifics, and that the mating system likely is polygynous.