The facilitation of word processing by sentence context reflects the interaction between the build-up of message-level semantics and lexical processing. Yet, little is known about how this effect varies through adulthood as a function of reading skill. In this study, Participants 18–64 years old with a range of literacy competence read simple sentences as their eye movements were monitored. We manipulated the predictability of a sentence-final target word, operationalized as cloze probability. First fixation durations showed an interaction between age and literacy skill, decreasing with age among more skilled readers but increasing among less skilled readers. This pattern suggests that age-related slowing may impact reading when not buffered by skill, but with continued practice, automatization of reading can continue to develop in adulthood. In absolute terms, readers were sensitive to predictability, regardless of age or literacy, in both early and later measures. Older readers showed differential contextual sensitivity in regression patterns, effects not moderated by literacy skill. Finally, comprehension performance increased with age and literacy skill, but performance among less skilled readers was especially reduced when predictability was low, suggesting that low-literacy adults (regardless of age) struggle when creating mental representations under weaker semantic constraints. Collectively, these findings suggest that aging readers (regardless of reading skill) are more sensitive to context for meaning-integration processes; that less skilled adult readers (regardless of age) depend more on a constrained semantic representation for comprehension; and that the capacity for literacy engagement enables continued development of efficient lexical processing in adult reading development.