This dissertation investigates the relationship between customer loyalty cards and brand trustworthiness, focusing on a case study of Marks and Spencer. The study aims to analyze how loyalty programs, specifically the Sparks loyalty card, impact customer perception, brand image, and customer satisfaction. The research employs a descriptive research design and quantitative research techniques, including surveys of Marks and Spencer managers, to collect and analyze data. The dissertation explores the concept and terminology of loyalty card programs, their significance in business, and the benefits of the Sparks loyalty card. It also examines the relationship between loyalty cards and trustworthiness, proposing hypotheses about the positive impact of loyalty programs on brand image and customer trust. The study includes a literature review, research methodology, data analysis, and conclusions, offering recommendations for improving customer loyalty and brand trustworthiness within the organization. The dissertation provides a comprehensive overview of the subject, incorporating relevant theories and concepts to assess the effectiveness of loyalty programs in fostering customer loyalty and building a strong brand image.