To predict the audiological outcomes of 2 multichannel cochlear implants, a preoperative battery of historical, audiological, electrophysiologic, and psychologic variables from 48 postlingually deafened adults was tested in a prospective randomized clinical trial. Multivariate analyses were used to select and combine these preoperative variables in a predictive index that was significantly related to audiological outcome at 9 months. The preoperative variables included in the predictive index were duration of profound deafness, speech reading ability, residual hearing, cognitive ability, measures of compliance and engagement with treatment, and use of nonverbal communication strategies. The preoperative predictive index had correlations of .81 with the Iowa Sentences Test, and .78 with the NU-6 word understanding scores, both obtained in a sound-only test. Probability and percentile curves generated from these data offer considerable optimism in forecasting the range of likely audiological outcomes that would be realized by postlingually deafened adult candidates for multichannel cochlear implants.