Where animals avoid inbreeding, different mechanisms of kin discrimination can leave different “signatures” in the patterns of observed mate relationship. For example, consider a species with no paternal care. If females avoid mating with familiar individuals, one would expect a deficit of offspring whose parents are maternal half-siblings, but paternal half-siblings would be unfamiliar with each other and thus mate at the frequency expected by chance. If spatial cues are used to avoid inbreeding, females would be expected to produce few offspring with males (even unrelated males) living near the female’s birth site. We searched for these and other signatures with data from a long-term study of bannertailed kangaroo rats Dipodomys spectabilis in Arizona, USA, using a combination of intensive censusing, mapping of available dens, microsatellite-based parentage determination, and a randomization routine that determines the numbers of offspring expected if females in the population mate indiscriminately among the males available to them. The data are consistent with the hypothesis that kangaroo rats discriminate kin by association, rather than by using spatial cues or self-referential phenotype matching. Our randomization routine also demonstrates that in this species, dispersal alone is not particularly effective at eliminating opportunities for inbreeding. Our approach can be applied wherever the spatial distribution of individual mates and their pedigree relationships are known, and should be widely applicable as a means of assessing the degree to which both kin recognition and dispersal influence inbreeding.