There are limited studies of relationship marketing in Business-to-Consumer, especially in a bancassurance context, although this theory has been previously used in the marketing studies in the past. Thus, this study employed relationship marketing theory and related constructs to explain the success of bancassurance in Thailand. About 700 questionnaires were distributed but only 443 completed sets of questionnaires were qualified for SEM analysis after data cleaning process. Among the antecedents of relationship quality, only relational bonds were found to have a direct and positive relationship with the cross-buying intention. Other variables, such as source credibility and brand image, were found to have indirect effect on cross-buying intention through relationship quality. The results of this study contribute theoretically in the area of relationship marketing and relationship quality. Relationship marketing theory was proven to be a dynamic theory and still plays an important role in the twenty-first century, especially in the services sector area. Moreover, relationship quality between the bank and its customers helps explain the success of the cross-buying intention of bank customers in the Business-to Consumer context.