Customer relationship management (CRM) is a strategic tenet for many leading firms and an important area of research for marketing strategy scholars investigating strategy implementation. Yet, for decades academic and industry researchers have reported a high rate of failure for CRM implementation efforts. This dissertation describes a deep investigation of the microfoundations of strategy execution, using both inductive and deductive techniques. The three studies demonstrate the importance of a new strategy implementation construct called disciplined execution of strategy (DE), characterized through the lens of CRM strategy execution. DE is not the implementation of ongoing marketing activities, but is a marketing capability of interdisciplinary CRM teams that balances the demands of executing a new strategy with their need to protect ongoing customers relationships from the disruption that comes with change. DE is presented as a novel and compelling explanation for the variability of past CRM efforts, and as a promising prescription for practitioners to improve future CRM implementation results.