It was hypothesized that symptoms reflect a patient''s social competence or maturity level and that this maturity level is related to the diagnosis he receives. Symptom stales based on empirical relations between symptoms and competence levels were constructed for 3 spheres of functioning: thought, affect, and action. Results obtained with 504 psychiatric patients showed: placement on each symptom scale was significantly related to diagnosis; patients who could be rated on all 3 scales showed consistent placement across scales. This latter finding was interpreted as indicating that the maturity dimension is a pervasive one, thus lending further support to the view that maturity plays an important role in the process of diagnosis.