For buyer-seller relationships to allow for effective transmission and integration of resources, and for value creation, each partner needs to invest in the relationship and needs to make it easy for the other partner to access their resources. However, every investment is risky and it is not sure whether investment objectives will be achieved, so this paper addresses the question of which factors drive intention to invest into a customer relationship from a supplier’s perspective. We propose and test three factors as positive investment drivers: the relationship quality; the suppliers’ expectation of future access to the important intangible resources in their customers; and the relationship value perceived by the supplier. By analyzing interview and survey data from managers, the study finds support for the propositions. Relationship value and expectation of future access to the customers’ resources have direct effects on suppliers’ intentions to invest. Relationship quality also has a strong effect, mediated by the other two drivers.