Families, like persons, can be considered as unitary cases. Like persons, families can be classified before treatment begins in an effort to predict their responses and thus, to formulate the best treatment program. Although many classification schemes have been proposed in the past, evidence is presented on the first successful use to our knowledge of a family classification scheme to predict a family's response to a family-oriented treatment program. The classification scheme grouped families according to their typical style of adapting to new situations. A family's classification was based on its performance in a standard laboratory problem-solving situation in which its interaction patterns could be measured precisely and objectively. This approach to classification successfully predicted the family's engagement in a family-oriented, inpatient treatment program for adolescents.