The organization of mammalian auditory cortex shows species‐specific specializations as well as organizational rules common to all studied mammals. Electrophysiological mapping of the tonotopic representation in several species indicates that features common to AI include (1) orderly representation of the entire cochlea within AI, (2) representation of a one‐dimensional cochlear segment by a two‐dimensional cortical belt crossing AI, and (3) radial organization of sharply tuned neurons of similar best frequency through the depth of the middle cortical layers. For some species, the AI representations resemble scaled models of one another. In most species, there are one or more orderly cochlear representations adjacent to AI. Surrounding these highly ordered fields are other fields (the “belt region”) in which neurons may not be as sharply tuned for frequency, or in which the cochlear representation may not be as orderly. “Association” fields may represent further abstractions of acoustic information, and sometimes may integrate polysensory information. Comparisons of the cortical cytoarchitecture of many species suggest expansion of “association” cortex through mammalian evolution. A most interesting species‐specific specialization is human speech and its associated hemispheric lateralization.