A guild of wandering spiders was studied in an oak-tuliptree-maple forest in northern Delaware. Specimens were collected by pitfall trapping and weather data recorded at weekly intervals over the summer season (3 months). A seasonal peak in species diversity (H') and species richness in midsummer was significantly correlated with prey abundance but not with seasonal temperature, humidity, or rainfall. Annual patterns of detritivore productivity in temperate forests and their influence on niche partitioning and seasonal abundance of species are discussed as a possible explanation. Spatial differences in species diversity were significantly correlated with the amount of litter and a measure of habitat space, but not with microclimatic moisture and temperature, vegetative diversity, or prey abundance. Physical aspects of the litter habitat, either as structural microhabitats or refuges from predation, are suggested as being important in regulating within-habitat species diversity. Interaction of diversity-regulating environmental factors in space and time are discussed.