Competitive webrooming, the phenomenon in which consumers gather product information online but ultimately purchase the product in an offline store of a competing retailer, has gained traction and become a major threat for retailers. To gain a deeper understanding of its drivers, we surveyed 1081 retail customers about their most recent consumer electronic product purchase to examine the impact of channel-related aspects as well as retailer-related aspects – a dual approach that has not been applied previously. A channel’s anticipated after-sales service and price level are the strongest predictors for webrooming. Moreover, retailer aspects determine whether customers simultaneously switch retailer when webrooming. A retailer’s assurance of delivery, including payment modalities, return policies, and product obtainment, as well as competitive product prices motivate consumers to switch retailer when webrooming. These results suggest that customers have a fundamental need for certainty within and after the buying process, which can be satisfied by both channel and retailer. Additionally, this is the first study to empirically test for interactions between channel and retailer aspects, as they are likely to occur in real shopping situations. We identified two interactions: First, a retailer’s assurance of delivery can compensate for an anticipated lack of a channel’s after-sales service, dampening the impact of the latter on competitive webrooming. Second, retailer’s price attractiveness acts in a similar vein. Hence, to steer customers into channels and/or keep them with the company, retailers should emphasize their price attractiveness as well as assurance of delivery.