1 Transtheoretical Model: Readiness to Change in Psychiatric Patients with Substance Abuse The transtheoretical (TTM) model is a change model developed by Prochaska and DiClemente to guide behavioral changes in individuals. Behavioral change is a process that takes time through which an individual goes through stages of change (Prochaska & Velicer, 1997). Therefore, the theory can be applied as a change model among psychiatric patients with substance abuse because they are expected to undergo behavioral lifestyle changes that can influence their lives (Callaghan, Taylor, & Cunningham, 2007). In this paper, the description of the model will be discussed based on its purpose, origin, major concepts, propositions, assumptions and the context of use. In addition, this paper will explain how the theory can be utilized in influencing change in psychiatric patients with substance abuse. Description of the Transtheoretical Model Purpose of the Model The change model was developed to help influence positive behavioral changes in individuals who are willing to undergo change. It assesses the willingness of a person to adopt a healthier behavior and provides a guide to the processes or stages that the person is expected to undergo. Therefore, the main purpose of the transtheoretical model is to guide the change process of an individual. This model focuses on the decision-making of an individual other than the influences of the behavior (Dugdale, Elison, Davies, Ward, & Dalton, 2016). By utilizing the model, individuals are able to know the expected changes they are to undergo. This is provided through the description of the expected stages of change. The change has to be intended by the individual as the model only provides a guide to change. Resultantly, the theory is widely used in encouraging behavioral changes in patients who are willing to go through a change (Callaghan et al., 2007).