1- INTRODUCTIONAs the competitive environment has rapidly grown over the past two decades and seriously overshadowed the activities of private enterprises, unsuccessful CHANGES, especially in terms of instability and unsustainability of the achievements, have become a fundamental challenge for such organizations as private banks. The research conducted in this field indicates that planning, directing, and sustaining the ORGANIZATIONAL change results is very difficult, and pervasive CHANGES affecting the main elements of the organization do not meet the expected goals. Some researchers suggested that organizations have difficulty sustaining continuous improvement in the long term, especially after an initial period of two or three years. As in most cases, employees do not internalize the new CHANGES and behaviors as their norms and mental beliefs and do not use them as a basis for their subsequent behaviors. The results and achievements of CHANGES may become unstable and fade after a short time, and a return to prior behaviors may occur in some cases. Thus, the organization incurs significant financial and opportunity costs that weaken its competitive position. This is true for Iranian private banks as they do not depend financially on the government and are in a fiercely competitive environment. Therefore, the main questions are as follows: what are the strategies to achieve sustainable change, and what are their consequences in Iranian private banks? 2- THEORETICAL FRAMEWORKDifferent theories exist for ORGANIZATIONAL change, which can be used to support and guide research to find the roots and consequences of sustainable ORGANIZATIONAL change. Research on ORGANIZATIONAL change can be categorized into three types: 1) content models emphasizing the content and essence of change, 2) contingency models considering the context and environmental conditions, and 3) process models focusing on the stages of change. A review of different change models indicates that they focus only on the content, process, or implementation of change while not addressing the period after the implementation, including institutionalization and stabilization of change. Therefore, this research was conducted to bridge the existing gap and provide change managers and agents in Iranian private banks with a vision to understand deeply the strategies for sustaining ORGANIZATIONAL CHANGES and their consequences. 3- METHODOLOGYThe philosophical foundation of the present research performed in private banks was interpretivism with the qualitative approach, and the grounded theory strategy was used. In this research, the systematic approach of Strauss and Corbin was used. The samples were purposefully selected by conducting snowball sampling on managers and experts of the private banks of Iran who have experience working in at least one change program in the past ten years, provided that one year lasted since achieving the results. The ORGANIZATIONAL change experts and researchers who had significant experiences were interviewed with a semi-structured method. The sampling continued to reach data and theoretical saturation. The collected data were analyzed by open, axial, and selective coding processes using the MAXQDA 20 software. Lincoln and Guba's criteria (credibility, dependability, confirmability, and transferability) were used to validate the results. 4- RESULTS & DISCUSSIONThe research findings demonstrated that sustainable change is characterized by two features: stackability of change, including internalization of the change and its adaptation and alignment with the ORGANIZATIONAL components, and spreadability of change, including the ability to transfer experiences to other employees and apply the ORGANIZATIONAL change. According to the research findings, the strategies needed to implement sustainable CHANGES in Iranian private banks include 1) empowering employees through training and utilizing work teams, 2) empowering the organization by establishing a knowledge management system and motivational mechanisms, the mobilization of financial resources, the scrutiny, and explanation of the organization's strategic plan, leadership style, effective processes, and agile structure. The consequences of sustainable CHANGES include 1) employees' growth and excellence due to their increased psychological and behavioral maturity, 2) improved efficiency to increase financial resources and reduce ORGANIZATIONAL costs, and 3) improved effectiveness to satisfy the strategic stakeholders and gain a competitive advantage. The research findings are noteworthy in that sustainable ORGANIZATIONAL change is considered a way to increase the productivity and prosperity of human resources in the organization. 5- CONCLUSIONS & SUGGESTIONSThis research demonstrated that a change is sustainable and is institutionalized when it is internalized in employees' beliefs and becomes a basis for their subsequent behaviors. This is realized by applying employee and organization empowerment strategies. Therefore, it is suggested that change managers and agents in the country's private banks consider the empowerment of employees seriously by applying influential and continuous training and expanding teamwork by using the strategies identified in this research, and the empowerment of the organization by using a knowledge management system, motivational mechanisms, providing financial resources, checking and explaining the organization's strategic plan, applying an appropriate leadership style, effective processes, and structural agility.