The link of grammaticalization theory with Construction Grammar tends to be conceptualized in two ways in the literature: by integrating constructionalist insights into grammaticalization theory or by treating grammaticalization as part of constructionalization. This project follows the latter line in re-thinking the rise of hypotaxis from parataxis in Germanic through the example of V1-conditionals as in Should it rain, we'll stay at home. Using data from both recent and older German and English, the project will show (a) how the rise of this sentence type can be conceptualized as constructionalization, followed by post-constructionalization changes, and (b) how the grammaticalization of a V1 main clause as protasis fed into a larger constructionalization process from a specific discourse routine ("pragmeme"). The final aim is an account in terms of Diachronic Construction Grammar, highlighting the interaction of the changes in question with shifts in each language-specific constructicon.