This dissertation, focused on Sainsbury's, a major UK retail chain, investigates the influence of organizational culture on employee performance. The study begins with an introduction outlining the background, aim, objectives, research questions, rationale, and significance of the research, followed by the structure of the dissertation. Chapter 2 provides a literature review, exploring key themes and theories related to organizational culture, including its impact on employee behavior, productivity, and the importance of leadership. The research aims to understand the concept of organizational culture, identify factors affecting Sainsbury's internal culture, determine the relationship between culture and employee performance, and recommend improvements. The dissertation emphasizes the importance of a positive working environment and its effects on both financial and non-financial aspects of the organization, highlighting the need for organizations to carefully manage their culture to avoid negative impacts on employee performance. The structure of the dissertation continues to include a discussion on research methodology, data analysis, and conclusions with recommendations. The literature review examines various models of organizational culture, including clan, holacratic, meritocracies, Denison, and adhocracy, and it stresses the role of leaders in maintaining and shaping organizational culture.