Sociolinguistic studies of intensification have found that “really” is replacing “very” as the most frequent adjective intensifier across varieties of English. A variationist analysis of adjective intensifiers in Salinas, California shows similar trends and points to a pragmatic motivation for this longitudinal change. Asymmetries in the types of adjectives modified by intensifiers over apparent time reveal that subjective adjectives (e.g., “good”, “cool”) serve as the bridging context for the emergence and diffusion of “really”. Since the target scale associated with these adjectives is epistemically grounded, the contribution of intensifiers in this linguistic context is ambiguous between expressing a high degree on a scale and a high degree of speaker commitment. We argue that this interpretive ambiguity facilitates the diffusion of “really” and its subsequent encroachment upon the functional domain of “very”. We underscore the importance of attending to fine-grained meaning differences between competing forms as they can help us gain a richer understanding of how language change occurs through subtle shifts in both form and function.