The primary purpose of this study is to theoretically identify the key determinants of brand loyalty. Based on the investment model in social psychology, this article suggests that customers'attitudinal loyalty to a brand is weakened by the quality of alternative options but strengthened by their satisfaction with, and investment in, the brand. An online panel survey was conducted, and the data supported all hypothesized relationships. Collectively, satisfaction, quality of alternatives, and investment accounted for more than 74% of the variance in attitudinal loyalty. The findings suggest that the investment model may lend a theoretical foundation to the explanation of tourists'brand loyalty formation.