If you saw a patient who appeared to have more than one personality, what diagnosis would you make? And how would you vary your clinical approach? Data from 425 respondents indicated that the majority of psychologists believed multiple personality disorder (MPD) to be a valid but rare clinical diagnosis. Respondents cited extreme child abuse as the foremost cause of MPD. Approximately one-half of all respondents believed that they had encountered a client with MPD, whereas less than one-third believed that they had encountered a client who feigned MPD.