Gift giving is an effective means for strengthening interpersonal relationships; it also may enhance the relationships between gift buyers and gift companies. With an explorative interview study, a field study that combines propensity score matching with difference-in-differences estimation, and two experimental scenario studies, this dissertation shows that purchasing a gift (vs. a product for personal use) leads to a subsequent sales increase of 52%. Specifically, gift buyers increase their purchase frequency (21% lift), spend more per shopping trip (27%), and engage in more cross-buying (42%). The sales lift is particularly pronounced for novice customers, so gift purchases offer an attractive vehicle for engaging less experienced customers with the firm. Attitude formation theories suggests situational involvement, customer gratitude, and public commitment as mediating mechanisms that explain the positive impact of gift purchases on customers future purchase behavior. Gift purchase characteristics emerge as contingency variables that determine the strength of the mediating mechanisms. High social closeness of the gift recipient, assistance during the purchase process, and high visibility of the gift presentation positively influence situational involvement, customer gratitude, and public commitment, respectively.