This case study describes four therapy sessions with a mother and her drug-using son. Conducted over the period of a month, the counseling, which included two individual and two family sessions, helped determine the reasons for the son’s use of marijuana and cocaine; the factors affecting the change that occurred in the mother and son’s relationship; and the therapeutic interventions that relieved the son’s symptoms. The therapist’s work was informed both by the MRI interactional model and Murray Bowen\'s family systems model, which were used to attend to issues of communication and the mother’s differentiation of self. The case study used a time-ordered effect matrix and network to track the reduction of the son’s symptoms in connection with the relationship change between him and his mother.