It is uncontroversial that morphological processes can change phonological surface representations. However, some empirical evidence also suggests that morphological processes may trigger phonetically gradient processes, that is, processes that involve fine phonetic differences, but involve no change in phonological categories. Such findings challenge modular or discrete feedforward theories of grammatical architecture, which counterpredict direct interactions between morphology and phonetics. This article reviews some of the findings in this area, pointing to two types of difficulty in interpreting evidence of morphologically-conditioned phonetic gradience. The first one involves significance and replicability in experimental sciences, which become especially problematic when fine phonetic detail is examined and the magnitude of differences involved is very small. The second one concerns identifying what is causing the phonetic effects among a wealth of possibilities, including paradigmatic relationships, morphological structure, prosody, and informativity.