The decision on whether and to what extent they should implement cross-channel integration is a crucial and complex task for multi-channel retailers. Although prior studies have sought to identify key determinants of this decision, most are descriptive or draw on divergent theoretical perspectives. The authors provide a cohesive theoretical model from the perspective of innovation diffusion, including not only technology-related but also organizational and environmental factors. The empirical findings based on the observations in the U.S. retail sector indicate that retailers’ information-technology capabilities and private-label provision drive their cross-channel integration. Moderate diversity facilitates cross-channel integration more than does high or low diversity. Firms’ financial resources seem to be less important or unimportant at a low level of industry concentration, but may influence retailers’ cross-channel integration at a high level of industry concentration.