Understanding how short-term memory shapes sentence comprehension processes is a long-standing topic in psycholinguistics. This thesis pursues new insights on two facets of short-term memory's role in sentence comprehension: (a) The first four experiments search for, and obtain, concrete evidence that locality effects, or increased integration difficulty attending increased dependent-head distance, occur even in simple sentence, where memory-based theories predict them and other theories (such as experience- or expectation-based theories) do not. (b) The remainder of the thesis investigates the functional interplay between similarity-based interference and expectation. Expectation has been argued to facilitate processing at verbs by pre-activating lexical representations, and similarity between representations of recently linguistic context has been shown to slow processing of verbs by slowing integration of its dependencies with arguments; yet the relationship between these two potentially interacting processes has received neither theoretical nor empirical attention. This thesis presents a novel eye-tracking experiment that finds effects of both expectation-based facilitation and retrieval-based difficulty on the integration of a subject-verb dependency, but no evidence of an interaction. This evidence supports a simple model of expectation and retrieval interference in which expectation effects play out in early, lexical processing while dependency integration processes occur later without interacting with expectation. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]