Functional cerebral specialisation is a phenomenon of considerable relevance not only to those investigating normal brain function, but also to scientists who study and treat clinical populations. This special issue of Laterality brings together contributions both from researchers studying human populations and those using animal models, and includes a discussion of the current important issues in the field of lateralisation of function. The papers address the origins of laterality, and the nature of lateralised functions in various species as well as relations among the different forms of lateralisation. Included are such topics as lateralised memory processes, early experiential effects on laterality, the genetic basis of handedness, perceptual processing in the haptic or visual domain, and learning. Comparisons between human and nonhuman primate findings and implications of these findings for our understanding of the