Today, many firms develop and implement key account management (KAM) programs to manage the relationships with strategically important customers. The implementation of KAM programs requires the configuration of special activities, actors, and resources dedicated to key accounts, which poses major challenges for managerial practice. Firms often underestimate the fundamental organizational change required for a successful implementation of KAM. The objective of this article is to advance extant knowledge on KAM by developing a framework that outlines essential processes to assess and diagnose barriers to KAM implementation. In our article, we integrate extant knowledge on KAM organization and enactment, and we propose a four-step process model that links the concepts of embeddedness, differentiation, integration, and alignment. In addition, we illustrate our model in a case study analysis with a large-scale European industrial company. The findings of our study allow us to derive avenues for further research on KAM implementation as well as implications for management practice.