Although some practitioners are beginning to use single-system evaluat
ion methods with various client problems and treatment perspectives, m
any practitioners are still unsure about how to use these methods with
more than one individual in a client system. The authors demonstrate
the applicability of a practice-driven, single-system evaluation to co
njoint therapy. The primary focus of this integration of practice and
research methods is to assist the practitioner in making informed trea
tment decisions based on the couple's progress toward the attainment o
f measurable treatment goals. A case presentation using a cognitive-dy
namic approach in treating marital disaffection illustrates the specif
ic activities involved in an evaluation.