AbstractThis paper shows that models of sentence comprehension based on “weak interaction” between syntax and interpretive processes are theoretically well-founded. According to this theory, local syntactic ambiguities can be resolved as soon as they are encountered in a single left-to-right pass through the sentence, by distinguishing the alternative partial analyses on the basis of their semantic and referential appropriateness to the context of utterance. This “incremental-interactive” theory is compared with an alternative serial structural strategy-based model proposed by Frazier and others, including Clifton and Ferreira. Particular attention is paid to a component of this theory that has been called the “Thematic Processor”. This component has hitherto remained somewhat under-specified, but we examine a number of possible interpretations. We argue that the only reasonable interpretation of the thematic processor is as a mechanism identical in every respect with the incremental weakly interactive processor that we ourselves propose. We conclude that the additional postulation of parsing strategies, in particular Minimal Attachment, may be unnecessary.