Preliminary experiments were performed on the discrimination of interaural time and the discrimination of interaural amplitude for lateralization images both on and off the midline, using a common set of subjects and a common experimental configuration. The results are compared with some previous work on interaural discrimination and time intensity trading and with the prediction of the EC model relating interaural time discrimination to interaural amplitude discrimination. © 1969, Acoustical Society of America. All rights reserved.