The concerns with much OD research has underscored the need for a model of planned change. Because of the lack of a generic model, change process and intervention theories are often recklessly combined and fail to integrate OD theory, research, and practice. The Porras and Silvers model of planned change provides a useful framework for introducing change within an organizational setting.

The model distinguishes two types of intervention strategies—OD and organization transformation (OT). Porras and Silvers feel that OT should be a separate entity because the underlying theories and concepts are not as well defined as OD. It also shows the relationship between change interventions and organizational target variables. Vision variables are the underlying organizational values, beliefs, and principles that guide management decisions and provide the foundation for the purpose and mission of an organization.

Target variables include policies, procedures, work rules, job descriptions, formal reporting lines, social factors, and communication patterns. In essence, these form the framework for organization structure. The third part of the model focuses on the types of individual cognitive change. Porras and Silvers conceptualize cognitive change as the alteration of a person’s perception of some existing organizational variable or paradigm. Each level of cognitive change represents change as an occurrence on a broader scope, from individual to organizational.