This special issue examines recent advances in our understanding of how interaction between the cerebral hemispheres can change with age. The articles investigate some of the important questions regarding integration of information between the hemispheres from a lifespan perspective ranging from childhood through the older adult years. They include information from individuals of differing age with intact commissures, those with congenial absence of the corpus callosum, and those with presumed disease-related callosal damage--allowing for the strength of converging perspectives.