Through our experience gained with adult patients during the last ten years we have found it useful to divide them into three groups:- 1--Those who are very strongly motivated to accept orthodontic treatment for cosmetic purposes and with whom treatment will usually be satisfactory. 2--Those who are suffering from anxiety states and who have developed a fixation on a dental fault and with whom it is very unwise to begin treatment before a favourable psychiatric report is obtained. 3--Those patients who need treatment before prosthetic rehabilitation or for other physical disorders and in whom treatment may or may not be successful, depending on the degree of co-operation shown by the patient and on good teamwork between dental specialists.