Peters' note is valuable as an overview of current knowledge about filler syllables, in part because it clarifies how much we do NOT know about these elements. The note also points to the potential value of filler syllables for theoretical accounts of early language development, including contrasting predictions derived from nativist accounts against those that Peters describes as ‘constructivist.’ Characterizing the nature and function of filler elements could be very helpful for distinguishing these accounts, particularly if the focus is on identifying changes that might reflect a transition from phonological to morphological functions. As Peters indicates, differentiating these functions is unlikely to be easy. Indeed, it will be particularly difficult if Peters is correct in believing that the morphological categories are constructed; that position predicts a gradual transition from phonological to morphological functions and thus a period during which filler syllables are neither phonological nor morphological but, instead, somewhere in between.