Extent of edge habitat is often defined arbitrarily from a boundary between 2 habitats. Instead, we assessed whether space use by white-footed mice (Peromyscus leucopus) responded to habitat changes along an edge-to-interior gradient in eastern deciduous forest. We measured movement distance as mean squared distance from center of activity (MSD), microhabitat variables, and distance to nearest conspecific neighbor. Distance of center of activity from the habitat edge was not affected by animal age (e.g., body mass). Male MSD did not change along the habitat gradient. Female MSD increased with distance from habitat edge, was negatively related to vertical cover, and was positively related to diameter at breast height of trees. Increased MSD in forest interior may reflect lower availability of nesting sites or diet items. Decreased MSD at forest edge may reflect higher vegetative cover that provided more food or behaviors by mice to avoid edge predators/parasites. Female use of vertical habitat increased with distance from habitat edge, and was related to fewer trees, less woody debris, and smaller distance to nearest conspecific neighbor. Fewer trees and less woody debris could negatively affect availability of nesting sites, travel routes, or diet items, hence greater use of vertical habitat. The nearest-neighbor effect may indicate intraspecific competition from lower availability of resources in forest interiors. Such responses in space use along a habitat gradient indicated that defining edge habitat as an arbitrary distance from a habitat edge may be insufficient to understand ecology and behavior of small mammals.