Yvonne Agazarian uses a synthesis of systems theory and object-relations theory to provide a schema for therapeutic interventions in each phase of group development.

Lewin's work has had an especially significant impact on the work of Yvonne Agazarian, and it is important to see her efforts against the backdrop of Lewinian field theory, although she has gone well beyond Lewin in her recent systems theorizing. Agazarian is always and insistently focusing on the group and its subsystems. She has an implicit faith, which derives from Lewin, that individual pathology will receive proper attention if the group dynamics are addressed. She thus focuses away from the individual members, a strategy which she maintains is less intrusive and less pathologizing (less conducive to iatrogenic illness via self-fulfilling prophecy) than individual-focused methods of group treatment.

Second, Agazarian's view of group development owes a major debt to Bennis and Shepard's theory of group development. Bennis and Shepard studied changes in the group field (as formulated by Lewin and by Bion) over time. For Bennis and Shepard it is the group system which evolves, and in that ever-changing context, the person grows, resolves conflict, adapts to shifting norms. This view is in sharp contrast to both Bion and Freud, who saw group formations as inherently static and change almost exclusively as a modification of the psychical structure and function of the members of the group.