Clarification requests, queries posed in response to a “problematic” (misheard, misunderstood, etc.) utterance, are a challenge to mainstream semantic theories because they call into question notions such as “shared content” or “the context.” Given their strong parallelism requirements, elliptical clarification requests introduce in addition significant complexities concerning the need for long-term maintenance of non-semantic information in context. In this paper, we consider a puzzle concerning the emergence of elliptical clarification requests in child English: Data from the Belfast and Manchester corpora (...) from CHILDES demonstrate that reprise fragments, the highest frequency clarification request construction among adults, emerges with significant delay in comparison with reprise sluices, bare wh-phrases used to request clarification. This is a puzzling finding a priori: first, since reprise fragments are by most plausible measures the most readily available clarification request form in that it involves mere repetition of material primed by the previous utterance and children have the ability to repeat parts of the previous utterance from the earliest stages of speech. Moreover, as we show, reprise fragments predominate—in some cases vastly so, over sluicing in the input of fragmentary clarification requests available to the child—and it would, therefore, be difficult to construct an explanation for order of emergence primarily based on frequency of the construction in the children's input. Our account is based on grammatical explication of the difference between the constructions, how constructional difference is represented in a hierarchy of constructions, and in terms of a notion of semantic complexity that suggests reprise sluicing is, in fact, less complex than reprise fragments. (shrink)