In this study we investigated how vocabularies of patients, as well as therapists, are related to outcome of psychotherapeutic treatment. For this purpose 80 transcripts of the ten most and ten least improved patients of the Penn Psychotherapy Project (PPP) were included in the Ulm Textbank. In addition to the total amount of speech, different vocabulary measures, such as the "private vocabulary" and the "shared vocabulary" of patient and therapists, were applied to the transcripts. Furthermore, the "Regressive Imagery Dictionary" "RID" was applied as a content analytic approach, measuring primary and secondary process content in a given text. Significant correlations of these variables with the PPP outcome measure "residual gain" were found, indicating, that successful therapists tend to accommodate more to the language of their patients compared with their non-successful colleagues.