Conventionally, identity centrality has been conceived of as a stable and transsituational construct, with situational variability in identity centrality treated as being of little informational value. In contrast to past research, we develop a theoretical model arguing that a portion of within-person variability in identity centrality is systematic and meaningful. Drawing on identity control theory, we examine the withinperson relationship flowing from perceived role progress to state identity centrality, which is conventionally viewed as reverse causal at the between-person level. We further explain the intermittent effect of an intense positive emotion-passion for the role-and investigate the contingent effect of in-role effort. The results from 2 repeated-measures studies showed that a significant proportion of total variance in identity centrality occurred at the within-person level and perceived role progress influenced state identity centrality by engendering passion for the role contingent on in-role effort. We discuss the theoretical and practical implications of our findings for management and organizations to inspire new intellectual debate and novel viewpoints to advance the microfoundation of identity theory.