This research examines leadership’s role in their organisation’s diversity management efforts. The management of a diverse workforce in today's organisations is becoming increasingly complex. It needs to go beyond considering not only the surface-level dimensions of diversity, but also the hidden and dynamic deep-level diversity dimensions in organisations, that are considered complex systems. Surface-level diversity dimensions include gender, age, race, ethnicity, and accessibility. Deep-level diversity dimensions are the hidden values, worldviews, personality, and experiences of individuals in organisations. In today's socio-cultural context, the heightened awareness and interest in matters relating to equity, diversity, and inclusion (EDI) is driving organisations to seek ways to address how to manage their diverse workforce that will unlock the benefits that diversity has promised. Diversity management approaches that only consider surface-level dimensions are no longer adequate. To unlock further the benefits of diversity consistently in organisations today, diversity management approaches must include deep-level diversity characteristics. This shifts diversity management approaches that have managed the various surface-level diversity characteristics to approaches of managing for diversity that require an organization-wide approach. Diversity management today requires the senior leadership team to play a strategic role. As organisations adopt a more holistic and systemic approach to their diversity management efforts, it requires the leadership to strategically manage their organization’s diversity management efforts. This goes beyond the diversity initiatives such as creating policies, initiatives, events and programs that celebrate diversity to behaviours that foster a diverse and inclusive workplace. However, the strategic diversity leadership in their organisation's diversity management efforts has not been fully explored. This thesis seeks to explore two research questions. Firstly, it seeks to identify the factors that influence the three leadership dimensions of diversity management and the factors influencing the leadership’s strategic role in their organisation’s diversity management efforts. Secondly, it seeks to map the three leadership dimensions into an emergent model of leadership agency for diversity management. Drawing from the literature review, three dimensions addresses leadership’s strategic inclusive leadership. Leadership accountability, leadership approach and leadership focus for diversity management describe different facets of the leadership’s strategic role. Central to addressing leadership’s strategic role is to further the understanding the factors that influence leadership in their organisation’s diversity management efforts. Leadership agency describes the capacity and authority of senior leadership team to influence, to make strategic decisions and take action to meet their organisation’s outcomes and goals. In the case of diversity management, leadership agency describes identifying and understanding the factors that influence leadership in their strategic inclusive leadership. The research questions of this study identified the factors influencing leadership agency in three dimensions of diversity across the different levels of the organisation. It also proposes an emergent model that maps an organisation's leadership agency for diversity management that provides a visual and practical model of leadership’s agency for diversity management. The study uses complexity theory as its theoretical base within an interpretive philosophical base and constructivist paradigm to examine leadership agency for diversity management. This research provides insights into leadership agency for diversity management in today's organisations through a multiple case study method. Using qualitative methodology, ten organisations participated in this research to determine leadership agency for diversity management. This study makes original contributions by addressing the leadership’s strategic role in diversity management through the lens of complexity. It also contributes to the research into organisational diversity management theories by developing a practical emergent model that highlights the crucial role of leadership agency in achieving positive diversity management outcomes, especially addressing the complexity of diversity. The study uses a multilevel lens to explore how leadership approaches managing their diverse workforce. It proposes an emergent model of leadership agency for diversity management as a tool that can help organisations gauge their level of agency. This study underscores the importance of intercultural sensitivity development in future research on leadership’s agency for diversity management. Further theoretical development is necessary to enhance these findings' validity and reliability and identify leadership agency practices that support effective diversity management in organisations.