As family therapy becomes a serious intellectual disipline, the relationships among its leading variations require closer examination. To examine similarities and differences among four closely related approaches (brief, problem-focused therapy; structural family therapy; strategic family therapy; and systemic family therapy) and to determine if the therapy models are most closely related in theory, in practice, or considered variations on a common theme, representatives of four institutes where the models were developed completed a 60-item Family Therapy Questionnaire. Results indicated that despite common roots in cybernetics and systems theory, the four strategic systems therapies appeared to share less in concept than technique. The models shared a practical, strategic orientation to change, but differed in their conceptions of how problems were maintained systemically. In addition, the four approaches were closely enough related to the considered variations of a common clinical, if not theoretical, paradigm. The findings suggest that the systems therapies are growing rapidly, with developments in technique outstripping those in theory and research. (PAS)