Shell polymorphism in the land snails of the genus Cepaea has been studied for more than a century. Although these studies have taught us much about the ways in which evolutionary forces work at the population level, many problems are still unresolved. Studies of shell polymorphism, especially in populations living at the edges of the species’ geographical distribution, long-term surveys of morph frequencies in selected populations, studies of the dispersal abilities of Cepaea snails and of differences in physiology and behaviour among morphs will help to answer outstanding questions, which have direct relevance to our understanding of microevolutionary processes generally.