Outcome research was reviewed on the conjoint treatment of families that involved at least two generations. Results from studies without comparison groups show that conjoint family therapy has an impact that is similar, but not superior, to nonconjoint methods. Studies with comparison groups provide some evidence that conjoint treatment is superior to no treatment and to treatment with nonconjoint methods. Studies that examine the effect of factors (ie, patient, therapist, and technique) affecting the outcome of conjoint treatment show that variations in these factors do have an impact on the result. Identifying the proper criteria of change is important.