E-commerce is gaining ground and leaving the role of traditional brick-and-mortar stores open to question. With this in mind, a team of researchers performed a case study to determine what effects the store openings of one multichannel retailer of fashion, home furnishings and high-end accessories would have on its catalog and online sales. The opening of brick-and-mortar stores had positive and negative effects for the retailer, but complementary consequences clearly outweighed sales drops in individual channels: In the short term, only catalog sales declined slightly. But over time, both the catalog and online channels increasingly benefited from the presence of the new brick-and-mortar stores. Within 79 months, catalog sales recovered to a level that would have been expected had the store never opened and subsequently continued growing more than in a sample without new stores. An enhanced understanding of both positive and negative cross-channel effects helps retailers better anticipate and respond to changes in sales in existing channels when a new one is added. It is the basis for strategically managing a company’s channels as a portfolio rather than as separate entities.