The objective of key account management (KAM) is to reap the economic benefits of long-term relationships with important customers. Whereas researchers have devoted large efforts studying the reasons suppliers adopt KAM, practitioners are especially interested in organizational aspects related to the implementation of KAM. In addition, the complexity of the topic often leads researchers to examine just a single aspect or certain perspectives in more detail. Against this background, this chapter compiles important findings and systemizes them. The first section of the chapter lays the groundwork by defining KAM and connecting the KAM approach to related research areas and relevant theoretical concepts. The second and main section provides an in-depth discussion of the dimensions of KAM, including the determinants of KAM adoption, the design of KAM and its performance implications. The chapter closes with implications for managerial practice and an agenda for future research.