Collusion is defined as a resistance between therapist and patient in which the transference and countertransference become interlocked in a tacit agreement to avoid a mutually fantasized catastrophe. Collusions are possible because therapist and patient share an unconscious, fearful remembrance of the breakdown of the function of the primary object. Although usually described as destructive for the treatment, collusions might also protect the psychotherapy by preventing disillusions from occurring too quickly. It is argued that when the therapist has been sufficiently recognized as a container function, the progress of change can continue and often does so by means of a sudden shift generated by changes in the analytic setting. Theory is illustrated with case material from a patient suffering from chronic schizophrenia.