La Soeur (1645) is one of the liveliest and most successful comedies by Jean Rotrou. It is an ingenious adaptation, long unidentified, of an Italian comedy, La Sorella (c.1584), by the polygraph Giambattista Della Porta; sometimes it remains close to the original text, at other times it is bold in eliminating superfluous material and in imparting a convincingly French flavour to the dialogue. The introduction to this new edition assesses the originality of Rotrou's adaptation. The notes are devoted above all to linguistic questions and to the many exotic allusions found in the text.