With the advent of structural and then generative approaches, historical linguistics experienced a notable decrease in popularity during the 20th century. However, several linguists have since pointed out the importance of diachrony in linguistic inquiry, not only for its own sake but also for understanding present-day language states from a synchronic point of view. In this talk, I set out to demonstrate how historical texts can shed light on structural and psycholinguistic questions by studying recomplementation (e.g., “My hope is that by the time we meet that we’ll have made some progress”) in Old Romance. Looking at single- and multiple-complementizer structures in medieval Spanish texts – where recomplementation is widely attested, in contrast to modern written texts – I explore the possibility that recomplementation may consist in the use of grammar-licensed constructional shifts with the function of aiding communication in the face of working memory constraints. Under the assumption that the grammar of a language is a system emerging from the interactions of its speakers, I argue that phenomena such as constructional breaks and shifts can be more than mere “performance” phenomena as long as their occurrence is licensed by convention, as seems to be the case with recomplementation in Old Spanish. Thus, if the proposed interpretation is correct, this phenomenon provides further evidence of the role of discourse in shaping grammar.