Evaluation of the therapeutic alliance is crucial for understanding the therapeutic process and its results. However, few instruments are available in French. This article aims to validate a French short form of the Working Alliance Inventory (WAI). Unlike other questionnaires, the WAI is the most widely used in psychotherapy research as well as in social psychiatry. Confirmatory factor analyses were carried out on a sample of 150 client-case manager dyads in order to determine the validity of this short-form instrument. The results of these confirmatory factor analyses allowed us to answer different authors' questions (Horvath and Greenberg, 1989; Tracey and Kokotovic, 1989) regarding the factorial structure of the WAI. The results also indicated a unidimensional solution as being the most valid for the two samples. We suggest that, in future studies, only one score be considered for the evaluation of the WAI. We also suggest modifying two statements in the English and French versions in order to render a faithful comparison between the therapist and client versions.