The possibility that the time-course of auditory inhibition of return (lOR) might depend on the temporal or spatial predictability of the cue-target relation was investigated. In all the experiments, a location cue was followed by a target that was to be localized.An inhibitory effect became apparent ata longer stimulus onset asynchrony (SOA) when either the temporal or the spatial relation was predictable, rather than when either was unpredictable. A facilitative effect was apparent at a lOO-msec SOA, irrespective of the predictability of the cue-target relation. These results establish that the timecourse of the inhibitory component oflocation-based auditory lOR depends on the predictability ofthe temporal and spatial relations of cue and target. The theoretical implications of these results are considered, and a dual-process model of auditory selective attention is offered.Audition was, at one time, the modality of choice with regard to presenting information to study selective attention, and early models were based largely on the results of such experiments (e.g., Broadbent, 1957;Deutsch & Deutsch, 1963;Moray, 1974;Norman, 1968;Treisman, 1970). However, audition was soon replaced by vision as the preferred modality of study, with the result that, whereas much is now known about the selection of visual information, relatively little is known about the selection of auditory information. Interest in auditory selective attention has, however, been renewed in the last few years (e.g., Hafter, Schlauch, & Tang, 1993;Mondor & Bregman, 1994;Mondor & Bryden, 1992;Mondor & Zatorre, 1995;Rhodes, 1987;Scharf, Quigley, Aoki, Peachey, & Reeves, 1987;Spence & Driver, 1994;Woods, 1990). Much of this recent research has relied on a simple paradigm in which a single cue is presented, followed by a single target, about which listeners are required to make some type of detection or identification judgment. Usually, the time period between the onset of the cue and the onset of the target (stimulus onset asynchrony [SOA]) and the similarity of the cue and the target are examined for their effect on the speed and accuracy of responding to the target. This research has established, among other things, that the effect on performance of uninformative spatial and frequency cues varies as a function of SOA. Specifically, relative to performance for targets that differ from the preceding cue, performance for targets that are similar