This paper adduces evidence for and attempts to phonologically motivate a pattern of descriptive “retraction” of surface word accent in the Anatolian languages. It is proposed that the innovative accentual peak ( ictus ) in the relevant forms is due to Anatolian Default Accentuation , which applies when no constituent morpheme in a prosodic word is lexically specified as accented and assigns ictus to its leftmost syllable. Diachronic prosodic change is shown to result from the interaction of various morphophonological developments and the stable operation of this default accentual principle, whose effects in Hittite, Palaic, and Luwian require its reconstruction for Proto-Anatolian. Furthermore, the Anatolian evidence is argued to support Kiparsky and Halle’s (1977) reconstruction of the same default principle for Proto-Indo-European on the basis of Vedic Sanskrit and Balto-Slavic evidence.