Memory retrieval and probabilistic expectations arerecognized factors in sentence comprehension that capturetwo different critical aspects of processing difficulty: the costof retrieving and integrating previously processed elementswith the new input words and the cost of incorrect predictionsabout upcoming words or structures in a sentence. Althoughthese two factors have independently received substantialsupport from the extant literature, how they interact remainspoorly understood. The present study investigated memoryretrieval and expectation in a single experiment, pitting thesefactors against each other. Results showed a significantinterference effect in both response time to the comprehensionquestions and reading time at the last (spillover) sentenceregion. We also found that the interference effect on readingtime (but not on comprehension question response time) wascanceled when the word at the retrieval site was highlypredictable. Overall, our findings are consistent with thehypothesis of a modulatory effect of expectations on memoryretrieval and with the idea that expectation-based facilitationresults from pre-activation of the target word ahead of time.