Prior to 2013, only 5 verified records of the Common Sharp-tailed Snake (Contia tenuis) existed in western Washington State, with only 1 observation from the San Juan Islands. Our objective was to broaden our knowledge of the Common Sharp-tailed Snake in the San Juan Islands. We installed cover boards in suitable habitats and checked them as circumstances permitted. We engaged local landowners by providing them with cover boards and asking them to check the cover boards to increase the likelihood of detection. We recorded 9 Common Sharp-tailed Snake observations between 2013 and 2017, including the 1st record for San Juan Island on Cady Mountain. We also observed the species on Mount Dallas and Young Hill on San Juan Island, and we increased the area of occupancy on Turtleback Mountain on Orcas Island by discovering 2 new sites. Conifer-encroachment resulting in habitat loss, along with house cats may threaten Common Sharp-tailed Snake populations at these sites. More study of these threats is needed to inform Common Sharp-tailed Snake management. Our findings imply a broader occurrence of this species in the San Juan Islands. We recommend broader surveys of occupied and other islands in the group to refine our knowledge of the distribution and habitat use of this species.