Abstract: Although administrative law doctrine requires courts to defer to an agency's reasonable statutory interpretation, the doctrine is unclear as to whether an agency gets less deference when it changes its own prior interpretation. We formally analyze how judicial deference to revised agency interpretations affects those interpretations' ideological content. We find a non-monotonic relationship between judicial deference to inconsistent agency interpretations and interpretive extremism. This arises because as courts become less deferential to revised interpretations, the initial agency finds a moderate interpretation that will not be revised more appealing. Normatively, our results suggest that an interest in responsiveness of interpretive policy to the preferences of the incumbent leadership favors deference to revised interpretations, while an interest in ideological moderation favors a somewhat less deferential posture to interpretive revisions.