Acoustic emissions are generated at the sites of the fundamental processes resulting in material wear and so are an attractive possibility for continuously monitoring wear and for basic studies of the wear process. Changes in wear rate and acoustic emission activity were measured across the mild-severe wear transition in the sliding of metals. The intent was to characterize these changes in wear behavior in terms of acoustic emission characteristics and to determine the usefulness of acoustic emission measurements for the study of wear. Experimental results showed that changes in acoustic emission count rates correspond to changing wear rate. Acoustic emission amplitude distributions as well as acoustic emission energy measurements indicated a strong potential for the use of these two parameters in the identification of different modes of failure during the wear process.