Hygromia striolata (C. Pfeiffer) is polymorphic for shell and mantle colour. Thirty-two samples were taken from natural populations in the region of Malham, Yorkshire. The samples were taken in pairs, one member of each pair from a habitat with a relatively dark background and one from a nearby habitat with a relatively light background. In general, samples from “darker” habitats had higher proportions of the dark-shelled and dark-bodied morphs. These associations are highly significant, and they can most easily be explained in terms of visual selection by predators.