Dermacentor albipictus (Packard) is an obligate, hematophagous ectoparasite commonly found on large ungulates in North America. At high infestation levels, the winter tick is known to cause severe pathology and may transmit diseases to its hosts. Knowledge of the genetic diversity in this parasite will allow us to accurately identify the tick to species and better understand how it interacts with its hosts and surroundings. In this thesis, I developed and used 14 microsatellite loci to re-examine the species boundaries and to investigate host specificity in this tick. I confirmed that D. albipictus consists of a single species but exhibits extensive genetic variation that is more associated with geography than host species. Information on species boundaries, geographically-associated genetic variation and extent of host specificity in winter ticks can have important implications in pest control and further research is desirable.