The literature on frequency effects in lexical diffusion shows that even phonetically gradual changes that in some cases are destined to be lexically regular show lexical diffusion while they are in progress. Change that is both phonetically and lexically gradual presents a serious challenge to theories with phonemic underlying forms. An alternate exemplar model that can account for lexical variation in phonetic detail is outlined here. This model predicts that the frequency with which words are used in the contexts for change will affect how readily the word undergoes a change in progress. This prediction is tested on data from /t, d/ deletion in American English. Finally, the effect of bound morphemes on the diffusion of a sound change is examined. The data suggest that instances of a bound morpheme can affect the rate of change for that morpheme overall.