Relationship selling is a strategy of attracting suitable consumers and then establishing, sustaining, and strengthening relationships with them to achieve long-term satisfaction through mutually beneficial partnerships. For a firm to remain competitive over time, it must ensure its strategies are difficult for competitors to duplicate. Thus, relationship selling is leveraged as a tool for achieving sustainable competitive advantage. In today's competitive environment, customer relationships are expected; hence, the establishment and development of relationship metrics is not an anomaly within successful sales organizations. With product quality becoming a universal standard and no longer a major source of competitive advantage, firms are striving to escape the quagmire of the “commodity mentality” that has pervaded the market today. To differentiate themselves, a number of these companies are resorting to relationship selling. This chapter focuses on understanding relationship selling, its components, and processes, as well as how it contributes to sustainable competitive advantage.