It is proposed that negative capability, that is, the capacity for tolerating uncertainty, doubt and not-knowing, is a factor that contributes to a problem-solving approach utilizable in some aspects of the psychotherapeutic process. Negative capability can be demonstrated both in therapists and patients. An analysis of the functions of negative capability within the psychotherapeutic process shows five stages in its utilization. These are the activation of therapist's negative capability; which is followed by observations about the patient's response to his perception of the therapist's negative capability; then the therapist's clarification of the patient's problem contained within the patient's response; followed by a working-through by the patient and therapist of the problems which are demonstrated and clarified; and lastly, a transfer to or enhancement of the patient's use of negative capability as a continuing behavioural mode. Some theoretical bases for the concept of negative capability and its application as a factor of problem-solving within the psychotherapeutic process, are proposed. Clinical excerpts from psychotherapeutic work are given to exemplify the stages as defined above.