Purpose: While extant key account management (KAM) research provide considerable insight into specific aspects of KAM, no studies have yet offered a process model that concurrently addresses the three important characteristics of KAM (i.e., temporality, dyadic interactions, and account heterogeneity). To fill this void, the present research investigates an industrial seller's KAM practice from the alignment perspective to develop a comprehensive process model that depicts the important underlying characteristics of focal firm–key accounts dyadic relationships. Methodology: Employing a case study approach, the present study adopts in-depth interviews with eleven informants involved in four dyadic relationships, respectively. Multiple dyads interviews helped us determine whether the emergent themes are resonant across dyads. On the other hand, cross-dyad analysis helped us identify idiosyncratic KAM treatment among heterogeneous key accounts. Findings: Drawing upon the literature and the field data, this study reveals four different patterns of alignment (i.e., opportunistic alignment, passive alignment, mutualistic alignment, and compensatory alignment) that may be enacted in accordance with the different relationships developed with the individual key accounts. Across the four focal firm–key account dyads, this study further uncovers how various factors (i.e., idiosyncratic investment, power structures, behavioral norms, and commitment) precipitate different alignment patterns and drive alignment transitions over time. Practical Implications: This article suggests that a focal firm should manage its key accounts by aligning its value proposition with the specific desired value of each individual account and adjust its management approach based on different phases of dyadic relationship development. Originality Value: This article extends knowledge of KAM by concurrently addressing its dyadic and heterogeneous nature in a process model. The alignment-oriented view of KAM sheds light on the underlying characteristics of focal firm–key accounts relationships and contributes to our understanding of managing key account portfolios throughout the process of relationship development.