Experts in the fields of mammalian, reptilian, avian and amphibian brain development and in evolutionary biology come together to discuss approaches towards the possible origin of the cerebral cortex, with particular emphasis on theories of the mammalian cerebral cortex. It includes: critical examinations of methods used to study homology in the central nervous system, methods used in cladistic analysis, and up-to-date data is given on the earliest generated transient cells of the forebrain and on cortical organisation.