Language comprehension, or, the process of extracting intended meaning from an incoming linguistic signal, is a complex task involving an incrementally unfolding interpretation of words within their relevant context. In light of the complexity associated with such a task, it is truly noteworthy that, most of the time, the processes dictating comprehension are carried out rapidly, accurately, and with little apparent conscious effort. The goals of the work provided within this volume were to 1) provide new data that can facilitate discrimination between three different models of on-line syntactic processing, and 2) demonstrate that phonological information is an often-overlooked source of information that can influence language comprehension during both normal reading and the processing of syntactically complex garden-path sentences. Distinguishing between different accounts of phenomena related to on-line syntactic processing has traditionally been quite difficult. Although several theories of on-line syntactic processing assume the parallel activation of multiple syntactic representations, evidence supporting simultaneous activation has been inconclusive. In Chapters 2 and 3, the continuous and non-ballistic properties of computer mouse movements were examined by recording their streaming x, y coordinates in order to procure evidence regarding parallel versus serial processing. Participants heard structurally ambiguous sentences while viewing scenes with properties either supporting or not supporting the difficult modifier interpretation. The curvatures of the elicited trajectories revealed both an effect of visual context and graded competition between simultaneously active syntactic representations. The results are discussed in the context of three major groups of theories within the domain of sentence processing, strongly supporting interactive competition-based accounts of syntactic processing over various stage-based accounts. In relation to the second goal, although it is true that many factors have been demonstrated to affect sentence comprehension, the influence of phonological factors has been all but completely neglected. The aim of the research presented in Chapters 4 and 5 is to demonstrate that phonological typicality, the degree to which the sound properties of an individual word are typical of other words in its lexical category, can influence syntactic processing. First, it is demonstrated that nouns and verbs form separate partially overlapping but coherent clusters in phonological space based on their phonemic properties. Two separate studies demonstrate that phonological typicality affects reading times on target words that occur within a linguistic context heavily biased to contain either a noun or a verb. Finally, a fourth experiment demonstrates that phonological typicality can influence, both on-line and off-line, the processing of syntactic ambiguities arising from the lexical category ambiguity associated with noun/verb homonyms. Overall, the results of the studies presented here provide strong evidence for a dynamic, highly interactive account of syntactic processing in which any salient and reliable source of information, even information phonological in nature, can aid in the pursuit of accurate, effortless sentence comprehension.