In the last quarter of the 13th century, a group was formed in Milan around memories of Guglielma, considered as a holy woman. Besides mainstream forms of cult, esoteric beliefs about Guglielma came into being, and a small network of people began to claim that Guglielma was a female incarnation of the Holy Spirit. Her followers had the project of establishing a new order in the Catholic church with new gospels, new apostles, a new hierarchy and a female pope. This article aims at a reconstruction of the group in the process of its emergence, reconsiders the source basis of various statements in existing literature, and arrives at the following conclusions: (1) by her way of life, Guglielma stimulated the birth of a congregation venerating her memory, but she was not the author of teachings associating her with the Holy Spirit; (2) in spite of the obvious importance of Andrea Saramita and Mayfreda da Pirovano, there are also other devotees of Guglielma who creatively contributed to the group's conversations and activities, but were overshadowed by the inquisitors' search for heresiarchs and by subsequent historiography; (3) there is no other evidence for the Bohemian and royal origin of Guglielma besides the trial records, and this alleged origin is likely to be a pious legend of her followers; (4) contrary to the suggestions of several historians, the devotees of Guglielma did not intend to establish a purely female hierarchy in the Church; and (5) in their conversations, Guglielma's followers discussed the question of why the Holy Spirit could not incarnate in a man, and for the most part, they saw the female incarnation of the Holy Spirit as a logical outcome of the process of human salvation. In addition to our assessments of these issues, we use the records to draw some conclusions about the precarious process of group formation.