This paper explores the evolution of the conversational formula pues eso in Peninsular Spanish through the framework of constructionalization, so as to describe how form–meaning pairings have been consolidated. Additionally, the Val.Es.Co. model for discourse segmentation is introduced as part of the form pole in the construction. The findings suggest that PE has become a consolidated parenthetical, procedural device during the 20th century, but that previous centuries are also key in understanding how the new functions were developed from pues.