Although the relationship marketing literature acknowledges the importance of switching costs for increasing customer retention in general, little is known about its relevance in industrial markets. In particular, it is unclear whether switching costs and its dimensions impact relevant behavioral outcomes of buyer-seller relationships in business-to-business (B2B) markets. Against this background, our research intends to make two main contributions: Since we assume differential effects for different types of switching costs, our research first explores the dimensions of switching costs for the B2B domain. Second, it tests the relative impact of the dimensions of switching costs on business customers’ actual purchase behavior. Results suggest that switching costs in B2B settings are a multi-faceted construct, including (i) procedural, (ii) financial, and (iii) relational switching costs. Moreover, we find relational switching costs to be most important for securing B2B buyer-seller relationships since they impact a customer’s (a) share-of-wallet, (b) cross buying behavior, and (c) actual switching behavior. While procedural switching costs only influence share-of-wallet, financial switching costs solely impact customer’s cross-buying behavior across a firm’s product and services categories. These findings contribute to a better understanding about how to secure B2B buyer-seller relationships.