In this article one aspect of a big longitudinal study on discourse in therapy groups is presented: sex-specific language behaviour was studied in a qualitative and quantitative way. The following results are of great theoretical and practical importance: there are qualitative differences in the speech behaviour of men and women (expressed in a significantly different choice of the type of text used for the presentation of problems). There are class-specific differences between the sexes. Conclusive evidence of the interdependence of these two factors is provided by our analysis. The chosen topics are significantly different, and lastly, the effect of the therapy could be proved by comparing problem presentations in group therapy by one and the same patient on the same problem. Against the background of these results, group therapy in the form presented here appears to be an effective means of enabling a patient to acquire different, alternative behaviour patterns. The importance of such an interdisciplinary approach (socio-, text- and psycholinguistic criteria and methods were used) to language behaviour therefore is evident.