The life of Marguerite, called Porete, is remarkably obscure. All we know about her derives either from her book, the Mirror of Simple Souls, or from documents connected to her condemnation in Paris in 1310. For this reason, scholars are constrained to make guesses and suppositions about her actions. This paper aims in the first place at exerting a tighter control on the use of imagination in reconstructing Marguerite’s life. By making sense of some hitherto neglected details, it establishes a crucial fact. An intermediary stage must be posited between her initial condemnation in Valenciennes (before 1305) and her final trial in Paris. She certainly passed through Châlons-en-Champagne in 1308. This where she was seized by the local bishop, before being sent to Paris.