This thesis explores the processes of interpersonal communication and influence and its impact on the purchase of durable goods by Saudi consumers. It attempts to develop grounded theory about these processes and their effects on the purchase decision, using a qualitative methodology of semi-structured interviews in data collection, and a method close to that of Glaser and Strauss (1967)'s constant comparative method for data analysis. The first chapter in this thesis discusses the objectives of the research and the reasons for choosing the particular topic. Chapter Two provides an overview of the literature in this area and a framework for the research. Chapter Three discusses the methodology involved and the reasons for adopting this methodology. Chapters Six to Ten present the findings of this research. They explore the various ways through which Saudi consumers may exchange product information with other people, the reasons for doing so, the types of people with whom they tend to exchange consumption-related information, and the impact of this information on the purchasing decision. In addition to this 'informational' influence, the research suggests that there can be significant normative influence on the Saudi consumer's purchasing decision. Chapter Six discusses this normative influence and Chapter Seven discusses how this influence may function through social comparison processes, the type of comparisons in which Saudi consumers may engage, and the bases on which 'comparison other' may be selected. In general, the results of this research suggest that interpersonal communication can play a major role in product information transfer in Saudi society and that interpersonal influence affects pervasively various aspects of the purchasing decision. Chapter Ten discusses these various effects including those on the diffusion of new products. Chapter Eleven provides a summary of the findings of this research, its theoretical and practical implications and provides suggestions for further research in the field.