A primary objective of community ecology is to understand the conditions that allow species to coexist by identifying how co-occurring species use and share space and resources. The European pine marten (Martes martes) and the stone marten (M. foina) are syntopic mustelids with similar morphology and ecology for which differential habitat use, especially differential use of resting sites, appears to be the main driver underlying their coexistence. Organisms commonly respond to their environment across a range of scales and habitat selection is a hierarchical process where each level reflects distinct behavioral processes. We performed an optimized multiple-level (i.e., selection of home range in the study area and selection of specific habitat components within the home range) and multiple-scale study of resting-site habitat selection. Each covariate was tested separately across a range of prespecified scales and then combined into a single multivariable, multiscale model. The 2 species differed significantly in their habitat selection at both levels. Stone martens selected buildings, whereas pine martens selected forest patches. However, both species avoided open areas and selected shrubs and hedges, confirming that syntopy was likely to occur with possible interactions between species. Differences in the spatial scale of resting-site selection, when both species selected the same landscape elements, might also contribute to this coexistence. Overall, stone martens showed higher interindividual variability in habitat selection than pine martens, and this variability was influenced by age and sex. Whether this variability was due to a greater behavioral and ecological plasticity of stone martens or to interactions with pine martens forcing stone martens to use suboptimal habitat remains unclear. In addition, stone martens generally avoided areas associated with high trapping pressure. However, a percentage of subadult males selected these areas, which could have serious consequences for the stone marten population.